This seems fairly obvious, but I just discovered you can drag items from Stacks. So if you have something in your Downloads folder, for example, that you want to file, simply navigate to where you want to put the file, click on the Downloads stack in the dock, and drag the item you want to move from the stack to where you want it!
This works with the spring-loaded dock and folders as well. Drag an image you just downloaded from the Downloads stack onto the iPhoto icon, wait for iPhoto to come to the front, then drag the photo into the album you want; you've just filed the photo without ever going to the Finder.
Not the most splashy of new hints, but one of my favorite new features is having spell check 'unlearn' a word. I have often been too quick to add a word to my spelling list, to only later see that I missed a letter or something.
Now you can select a word, control-click on it, and choose Unlearn from the pop-up menu. Obviously this only works with words in the personal spelling list.
[robg adds: When I first tried to test this, I couldn't get it to work. That's because I was testing it in Mail, which will happily let you add a word to the Dictionary ... but they seem to have left out the unlearn ability. So I switched to TextEdit, typed in my incorrectly-learned word, control-clicked on it, and saw the Unlearn menu item. So you may find this doesn't work in every app; Mail and TextEdit are the only two I tried it in. Worst case, though, you can switch to TextEdit, paste your word, and unlearn it there.]
I was having major problems with Spaces today, and I didn't want to reboot my machine because I had a ton of tabs open in Safari. Spaces would not respond to Command-Tab or switching apps with the Dock. I was only able to activate Spaces with my hot key.
I looked through the processes, and there was nothing whose name contained spaces. I turned off Spaces in System Preferences and turned it back on. That didn't help either. I even ran the Spaces.app, but there is no way to force quit it. SO I went out on a limb and tried an old reliable method for fixing Mac window weirdness: I killed the Dock's process, causing it to restart. Viola! Spaces works fine now.
Apparently Spaces is merely a new feature of the OS X Dock. So if you find yourself in this situation, here's what to do:
Launch Terminal, in Applications » Utilities.
Type killall Dock.
The Dock will restart, and you'll be (hopefully) back in business with Spaces.
[robg adds: I had this happen last week -- I sent some windows to a number of spaces, and they just vanished. Each app's Window menu showed the windows, but they wouldn't activate. The Dock's contextual menus did the same. In Spaces' F8 mode, the windows were gone. Killing the Dock brought all the windows back (into space 1, but at least they came back). Note that the "cleanest" way to restart the Dock is to logout and login; alternatively, you can also kill it in Activity Monitor without using Terminal.]
I love scrollable Stickies, but the method of implementing it has changed slightly under Leopard, as there's a brand new Interface Builder in the XCode tools.
Back in December 2005, Rob Griffiths put together a wonderful walk-though on how to create scrollable stickies under earlier versions of OS X. Read through that article (or print it off) to get most of the information you need to do this.
Things change once you open up the StickiesDocument.nib file in Interface Builder. After double clicking on the Window box, press Shift-Command-I to bring up the Inspector ... and it's a very different Inspector from prior versions of Interface Builder.
In the Inspector (which should say Stickies Window Attributes at the top), click on the Connections icon in the mini toolbar (it's the fifth one over, represented by a blue circle with right-pointing white arrow).
In the Outlets section that appears, double-click on the text labeled Scroll View (not mScrollView). Now, click on the first icon in the mini toolbar (Attributes).
In the Scroll View section, check the boxes marked Show Vertical Scrollers and Automatically Hide Scrollers.
Now, quit the Interface Builder program, being sure to save when prompted to do so.
That's it! You'll now have Leopard Stickies with scroll bars that automatically appear if there's more text than what the window allows.
[robg adds: The writeup I did for Macworld was based on this hint, which covered a number of other things one could do to Stickies in Interface Builder; I'm not sure how many of those may still be possible.]
It seems in 10.5 the Application Switcher now receives dropped files -- drag a file, press Command-Tab, then drop the dragged file onto an application in the switcher window.
[robg adds: While testing this hint, I noticed another change in the app switcher: pressing "H" is now a toggle. In 10.4, pressing "H" would hide the currently-highlighted app in the switcher, but there was no way to unhide it again. In 10.5, "H" merely flips the hidden state of the chosen app. Note that this is not a duplicate of this hint, which simply noted you could drag, Command-Tab to a new app, then drop. Now, finally, you can drop directly onto icons in the Command-Tab palette itself.]
After that, type killall Dock to restart the Dock and see your new folder. The only thing is that I haven't found a way to have it show as a fan, it only shows in tile view. But it is already a nice trick.
[robg adds: Once the stack is created, control-click on it to reveal a contextual menu that lets you pick between recent applications, documents, servers, volumes, and items. Note that I've edited this hint to reflect the method shown by mithras in this comment to the Create a System Preferences stack hint.]
When using the Spaces hot key (F8), if you hold the key, Spaces will appear, then disappear when you release F8. This great when you just want to get a bird's eye view of stuff -- press and hold, view, release and Spaces vanishes. And, this works as expected with the Spaces plus Exposé tip (Show all windows). Press F9 while holding F8, and you'll see the All Windows view.
Also, another tip for those with notebook keyboards (or others?). On mine, F7 has a tiny icon of two screens. This makes an excellent 'icon' for Spaces, so I've re-assigned Spaces to that key. This also leave F8 for the Yahoo! Widget Engine.
[robg adds: In 10.4 (and 10.5), both Exposé and Dashboard also have this 'quick view' mode, accessed by pressing and holding their respective keys.]
If you are looking to add users to custom groups, take a look at this Apple support document. However, occasionally there is a need to add a user to one of the system groups. In 10.4, this was done with NetInfo Manager, but that is gone in 10.5. After poking around a few websites, I wasn't able to find any tutorials on it, so hopefully this will help someone.
Everything here should be done on the command line (I looked for a GUI way to do this, but couldn't find one). First start dscl like this:
$ dscl localhost
Then cd to the Groups node:
You can see all the groups using ls. Once you have found the group you are interested in, you can view all its properties with cat groupname. When you are ready to add a user (username) to the group (groupname), use the following command:
append groupname GroupMembership username
If you want to remove a member from a group, use the following command (be careful!):
delete groupname GroupMembership username
When you are finished with your changes, exit dscl by typing exit.
If, like me, you like to change your folder icons every now and then, you'll know that you need to Get Info on an icon file or an existing item (the source), click or tab to the icon in the Get Info window, then copy it and paste it onto the icon in the Get Info window of the item you want it on (the destination).
Well, I just discovered that you can simply drag an icon file onto the icon in the Get Info window of the destination item, and it changes it for you. You can do this with any file -- it simply copies the icon from that file onto the destination. Very handy! I have noted that this takes a few attempts in some cases, but not sure why, so have bugged it with Apple.