Unlike the previous built-in slideshow screensavers, Lion's slideshow screensaver is pausable by hitting the spacebar. In previous system versions, hitting any key would stop the screensaver. This is handy when people ask 'where is that,' etc.
I've seen suggestions that a key combination and clicking Purchased will allow downloading of Lion again. First the word I have in my copy of app store says 'Purchases.' Anyway, this didn't work for me using a NON-LION 10.7 system but I have figured out method that may or may not be well known.
I only started on this quest when I had problems burning a boot DVD of InstallESD. I figured the file was corrupt.
Method 1: Use a Mac with app store that has not downloaded Lion. Using the App Store account that originally purchased Lion, start your download. Apple allows the use of Lion on all your Mac for $30.
Method 2: Move Install Mac OS X Lion.app that you've perviously downloaded to the trash. The system will ask for the admin password. Now simply launch App Store and go to Purchases. Note the change from Installed to Install.
[crarko adds: Not a lot of new ground covered here, but there were a few submissions of variation of this hint so I took the most complete of the lot. What worked for me was to make sure I had a backup copy of the downloaded Lion installer on another drive. Then when the installer self-destructs you can simply put another copy from the backup on the next machine, rather than downloading again.]
Opening Spotlight (Default Cmd+Spacebar) and typing any search term brings up the standard Spotlight list of results.
Highlighting a result will bring up a sort of Quick Look or preview window to the left of the search results list.
Pressing the Command key will popup a dialog bar in the bottom of that preview window showing you the 'Last Opened' date. If you continue to hold the Command key, the dialog box will then scroll to show the File Path for the particular result.
Pressing the Option key after the and with the Command key will toggle between 'Last Opened' and the File Path much more quickly.
[crarko adds: When I tried this what I saw was a toggle between the file name and the path. Post your results in the comments please.]
By default, in Finder folders are shown in between all other files. alphabetically. There was a hint for Snow Leopard that showed how to show folders first in Finder, which is not working on Lion. This is because of the file:
In previous versions of OS X, you could specify in which space an application should open. With Lion, there is no such an option in the System Preferences.
Instead, Control+click the application's icon in the Dock and look in the Options sub-menu. There is a section called 'Assign To.' There you can assign the application to the current desktop (space), all the desktops or none.
The last option is the default value, where the application is open in the desktop focused at the moment of launch. If it is already assigned to another desktop, it will be shown as an additional option.
For example, if you want Tunes to open in your third desktop (assuming you have at least three desktops), go to the third desktop and then Control+click on the iTunes icon in the Dock, go to Options and then click on 'This Desktop.'
[crarko adds: I tested this, and it works as described. I like this interface change.]
On Lion, Expose and Spaces have received a major overhaul in the form of Mission Control. As usual they have included some nice subtleties in the way you can interact with it.
All the following tips apply when you already are in Mission Control and are from the perspective of someone not using gestures (no trackpad or Magic Mouse).
You can use the Spacebar on a selected window to Quick Look its content.
You can change the selected window (the one with the blue border) by using your mouse or by typing the beginning of the title of this window.
You can enter the 'Application windows' mode by hitting Command+`.
If you keep on hitting Command+` you will traverse all the open windows of an application for all the open applications on your system. Even applications with minimized windows are included.
Note that Shift+Command+` doesn't take you in the reverse direction.
[crarko adds: Post other tips in the comments, or submit a new hint if you find something major.]
Entering accented characters while using *any* keyboard layout is easier than ever, similar to using iPhone, iPad or iPod Touch.
Previously, to enter letters like é, ñ, ö, you had to learn one of several hints: option-key combinations, use the International Keyboard, use the Keyboard Viewer or change the keyboard layout to the appropriate one and then touch-type the keys you want.
But, 10.7 goes the route of the iPhone/iPod Touch/iPad software.
If you want an accent over the letter 'e' just hold down the 'e' key as if you wanted to type 'eeeeeeeee.' You will see a short list of accent marks, just find the one you want and type the number underneath it.
[crarko adds: I tested this, and it works as described. See this hint for some other ramifications of this feature.]
So you are trying to live with the 'upside-down' world of Lion, and it works OK with the trackpad on your laptop but not with your wheel-mouse? Take a closer look at the shareware utility USB Overdrive.
With USB Overdrive, it is possible to alter any button on any input device like your mouse, and you can define specifics for a particular mouse or input device to suit your need.
All I did was to alter Wheel up and Wheel down for my mouse to be the opposite direction, so that Wheel up is 'down' and Wheel down is 'up,' and I can still retain the regular behavior for other devices.
[crarko adds: USB Overdrive has been handy for many years, and it's nice to see it still is.]