Find Recently-used Apps and Documents in Snow Leopard
Snow Leopard's Recent Items menu item--located in the Apple menu--has a simple new ability that may come in handy if you use this menu regularly. By default, the Recent Items menu displays recently-used applications, documents, and servers, letting you easily access these items again. In OS X 10.5, that was all you could do with this menu.
In 10.6, though, you can use the Recent Items menu to locate recently-used applications and documents in the Finder. If you hold down the Command key, then activate the Recent Items menu, you'll see that the description for the applications and documents change. Instead of showing simply, for instance, Safari, the menu will now display Show "Safari" in Finder. Select it, and the folder containing Safari (most likely, your Applications folder) will open in Finder.
While not terribly useful for applications, this trick can be a time-saver if you're trying to track down a recently-used document, but you're not positive where it might be located on your hard drive.