Warning / Disclaimer:
This trick relies on what is probably a bug to work, and may cause problems depending on what target applications are doing at the time method is applied. The system will even provide a warning to that effect when you try to implement this hint. Proceed at your own risk...

If you have ever been in a situation where you had an application running which you did not wish to continually have to "Tab" past in the ⌘-tab application switcher, it can be removed by simply renaming it while it is running, then restarting the Dock (see below for more on how to do that). The final (important) step is to immediately change the program's name back to what it originally was.

The program will no longer appear in the application switcher nor the Dock. If the application is a permanent item in the Dock, its icon will remain, but the triangle indicating active applications will be absent. Clicking the Docked application's icon will activate the app normally, but the contextual menu will be empty. Interestingly, windows belonging to the application still appear in Exposé.

Notes:

• The Dock can be restarted using Activity Monitor (in /Applications/Utilities), AppleScript (tell application "Dock" to quit), or various commands using Terminal (also in Utilities; killall Dock).
• For obvious reasons, it will require Admin access to use this on programs in the global Applications folder, although I suppose a user could, in many cases, run and work on copies.
• To be more conservative, it may help to kill -STOP the process for the interval that the application's name is altered (ie. kill -STOP pid and kill -CONT pid to resume, where pid is the process ID of the program being skipped)
• The Finder seems to be immune to the effects of this trick.

[robg adds: Bravely, I tested this one (using a non-critical app) on both 10.3.9 and 10.4.2, and it works. As noted in the warning above, though, it's potentially dangerous and not something I would recommend doing (unless you're willing to take the kill -STOP step as well).]

If you download a text file from the internet, like a ReadMe or a .nfo file, it usually doesn't open in TextEdit unless you explicitly tell the Finder to do so for each and every file you download. You can use the 'Open With' contextual menu, of course, but this menu usually includes a lot of options for generic text files -- so it takes a while to display, and then to scroll through to find TextEdit. You can also, of course, help the Finder learn about each type of generic text file you may download (by using Get Info and changing the default application), but this can be tedious and you may not actually wish to change the default application.

The solution is to create a simple Automator action to open the currently selected file(s) in TextEdit, and install it as a Finder plug-in:

1. Launch Automator and click on Finder in the Library column.
2. In the Action column, drag Open Finder Items to the empty area on the right-hand side.
3. In the Action itself, click the Open with pop-up and set it to TextEdit (or the text editor of your choice).
4. Select File: Save as Plug-in.
5. In the dialog that appears, enter the name you want to give to the plugin (eg. View in TextEdit) in the 'Save Plug-in As' field, and set the 'Plug-in for' pop-up to Finder.
6. Click the Save button.

From now on, you can select any file or files you want to view, control-click on one of them, and select the option View in TextEdit (or whatever name you used) from the Automator sub-menu. This is much quicker than using the Finder's huge Open With menu.

Note: This hint was originally submitted by an anonymous contributor, with a link to a downloadable action. However, the link was broken, and there was no contact information included with the submission, so I couldn't contact the author. I thought the concept sounded useful, however, so I played with Automator for a couple minutes to create my own version of the action. So thanks to the submitter, whomever you were, for the idea to create this simple plug-in.

I like having the "Show item info" option enabled in the Finder's view options for the Desktop, but on the 160GB hard drive I have, it often truncates the middle of the text because the area isn't wide enough to show it all. This leads to it being nearly useless and ugly, since the text looks like "152.66 GB, ... .13 GB free." So I decided to see if I could figure out how to change the text.

While I wasn't able to figure out how to completely reformat the text (just showing the free amount would be good enough for me), I did find the string variable for the word "free." It is located in /System -> Library -> CoreServices -> Finder.app -> Contents -> Resources -> English.lproj -> Localizable.strings. Open this file in a Xcode or BBEdit, and find this line "IV9" = "free"; (line 490). Change it to "IV9" = "";, and you just saved an extra four characters. Now all useful information fits into the area provided.

As with all hacks like this, be sure to be careful, make backups, and proceed at your own risk. After you have made the change, just relaunch the Finder using the Force Quit dialog to see the change.

I've written an Automator workflow that can be used as a Finder plug-in to tar and gzip any selected files or folders.

First, download the action. After it's downloaded, do this to get it working:

1. Double click the tgz folder.dmg disk image to mount it.
2. From your home folder, make the following hierarchy of folders if it doesn't already exist: /Library -> Workflows -> Applications -> Finder
3. Drag the tgz.workflow workflow from the disk image into the Finder folder you just created.

Now you can select files or folders in the Finder, control- or right-click, go to the Automator sub-menu, and select tgz to compress them.

[robg adds: I've mirrored the action in case the above download link goes away some day. Since 10.4 now retains resource fork info with all the command line utilities, this should be safe to use on any files. I tested it, and was able to compress (and the decompress) a set of files without any troubles. Note that you can also put the workflow in your user's Library folder, following the same structure as above, instead of the top-level Library -- this would install it only for your user instead of all users on the system.]

One of the few things I like about Windows that I thought OS X was sorely missing was a Parent Directory button (a button that opens the folder containing the folder the current window is showing). So I created an Applescript application that can be put on the toolbar to do the same thing. Here's the code:

tell application "Finder"
  set fdir to the target of front window as text
  set fname to the name of front window as text
end tell
set AppleScript's text item delimiters to {""}
set x to (length of fname) + 2
set fdir1 to characters 1 thru -2 of fdir as string
if fdir1 is not fname then --is current window at root of hd?
  set up1 to (characters 1 thru -x of fdir) as string
  set AppleScript's text item delimiters to {" "}
  tell application "Finder"
    set target of front window to up1
  end tell
end if

I also zipped the script's source code and the compiled application into a 22KB archive if you want to try them the easy way. This is my first time using AppleScript, so it's probably a bit rough (and it only has the standard AppleScript icon).

[robg adds: There's a built-in "show parent folder" command in the Finder; Go -> Enclosing Folder, or Command-Up Arrow. But as far as I can tell, there's no simple method to get that command into a toolbar button (but I am far from an AppleScript expert). You could use UI scripting to select that menu item, but that seems like more work than the above solution...]

I found this out when I was trying out Finder shortcut keys. If you have any Finder window selected, and you hit Command-Shift-Up Arrow, it will take the focus off the current window and select the first icon on the desktop, usually the Mac HD icon. A simple little shortcut that might come in useful sometime.

[robg adds: I thought we had this documented here somewhere, but a search seems to show that it's not yet listed. On my 10.4 machine, the first icon on the desktop isn't highlighted automatically; I have to hit Tab to actually highlight the first item.]

I use both an iBook and a Windows-based laptop at work, and it's a must for me to lock the screens on both machines before leaving my desk. I'm a keyboard shortcut junkie, and I quickly became envious of the Ctrl-Alt-Del-Spacebar combo that I could use in Windows XP to swiftly lock the screen (muscle memory is a great thing). So I worked out the following method to enable a keyboard shortcut that locks the screen in OS X -- and no scripting or work in the Terminal is required.

1. Open the Keychain Access application (/Applications/Utilities/Keychain Access).
2. Open the Preferences panel (menu: Keychain Access->Preferences).
3. Make sure "Show Status in Menu Bar" is enabled.
4. Now close the Preferences panel and then the Keychain Access application.

If you click on the Keychain Access menu extra that should have appeared in the menubar (it looks like a tiny lock), you can try pressing the "Lock Screen" option: this will, as you'd expect, lock the screen.

The Finder uses animation, for example, to provide some visual feedback with the "expansion" effect between icon and window that is seen when opening files or folders, or strictly for eye candy, such as when certain "disclosure triangles" are opened or closed.

If you are willing to sacrifice the visual feedback, disabling animation can provide a snappier experience, which may be of benefit to slower systems. Opening a single folder seems faster, and opening a multiple selection of folders is measurably faster (depending on the system's speed and number of folders). To disable animation in the Finder, open the Terminal (in /Applications -> Utilities) and enter this command:

defaults write com.apple.finder DisableAllAnimations -bool true

To selectively switch off just the superfluous animation when clicking on disclosure trinagles in "Get Info" (or the preview pane for files in Column View), use this command instead:

defaults write com.apple.finder AnimateInfoPanes -bool false

Moving in the other direction, for something completely useless, Finder also offers a "slow motion" mode similar to what is available for the Dock when the Shift key is depressed while activating Exposé or minimizing windows. In this case, the command is:

defaults write com.apple.finder FXEnableSlowAnimation -bool true

To see the effect, hold down the Shift key while opening a file or folder on the Desktop, closing a Finder window, or clicking a disclosure triangle in Get Info or the preview panel of Column View. The changes above require the Finder to be restarted (or the user to log out and back in).

[robg adds: These all worked for me in 10.4. To restart the Finder, you can hold Option then click-and-hold on its dock icon and select Relaunch ... or use Activity Monitor ... or type killall Finder in the Terminal. You can reverse any of the above settings by repeating them, but change true to false. Remember to restart the Finder again...]

The quickest way I have found to make Command-F default to a name search is as follows...

First, create a smart search (folder), get all the settings the way you want (including the window size, the results bars collapsed or expanded, etc.), put something like Type Filename Here in the search box, and save it as Filename or something. Let it save in your default Saved Searches Folder.

Then, go to that folder, copy the file Filename to the desktop, rename it to default_smart.plist and copy that file to the Resources folder in the Finder app. To get there, navigate to /System -> Library -> Core Services, control-click on Finder, and then navigate to Contents -> Resources. Authenticate when asked, and then use the Activity Monitor or Terminal to restart the Finder. Your new defaults should now be working when you hit Command-F.

[robg adds: This worked as described, though my Finder crashed the first time I hit Command-F ... but I hadn't restarted it myself manually, either (whoops). It's been working fine since then, though.]

When you type cmd-F in Finder, you are presented with two already filled-in criteria; Kind: Any and Last Opened: Any Date. While it's nice as a first-timer user to see the options available, we would like to change this default to something more reasonable.

A reasonable default would be a search without any criteria. I'll show you how that can be done, as well as how to set it to my favorite: Items opened today. The interesting file we have to change is:

/System/Library/CoreServices/Finder.app/Contents/Resources/default_smart.plist

To find this file, select the path in Safari (or other Cocoa browser) and choose Finder -> Reveal from the Services menu (in the application's menu). Copy the file to a working directory, for example, your home folder. This file can be edited with the Property List Editor if you have Developer Tools installed, but it's also easily edited with a Text editor -- you just have to be careful about syntax.