Check out Gary's list of apps that he suggests most people install on a new Mac on the first day. The list includes some utilities and browser plug-ins. You can get the links and make your own suggestions at http://macmost.com/must-have-lion-apps
The Resume feature in Lion allows you to quit applications and then run them again with your windows intact. Any documents or windows you had open before will open again the next time you use the application. This can be disorienting at first, but it can also be useful. Find out how to quit applications and have them start fresh next time. Find out how to disable the Resume feature if it is not for you.
Performing quick by complex searches in the Finder and in Mail is easier in Lion because of the new search tokens feature. You can build queries using text, dates and file types right in the search field.
Learn how to use the new Arrange By feature of the Finder in Lion. In addition to sorting your files, you can also group them by kind, size and other attributes. But using Arrange By can conflict with how you want to sort files in list view.
Besides large new features in Lion, there are many small changes. Check out 10 interesting and useful new things in Lion.
Lion Mail's new interface is different from previous versions of Mail. Learn how to use the three-column view. See how you can use the Favorites bar to make the mailbox column unnecessary. Learn about the Archive function and how to use keyboard shortcuts to move messages into mailboxes.
Learn the basics of Versions, a new feature in Lion that saves multiple copies of your documents as you work. Gone are the Save and Save As commands we have been used to for years. Learn how to use the new Save, Save a Version and Duplicate commands that give you a safety net while you work.
Lion includes Launchpad, a new way to find and run applications. You can view the icons of all your applications quickly by running Launchpad and flipping between pages of icons similar to the Home screens on the iPad and iPhone. You can organize your icons in app folders. Apps purchased in the Mac App Store are automatically added to Launchpad. But using Launchpad is optional as you can still run applications using the Dock and other methods.
The AirDrop feature of Lion allows you to send files between Macs. It works without a shared wifi connection, but requires two Macs that have very recent wifi hardware.
Get to know the new Lion gestures. You can use a trackpad on a recent MacBook or a Magic Trackpad to navigate around in Mac OS X 10.7 Lion. You can also do some gestures with a Magic Mouse. See where to enable and customize gestures.
Check out Mission Control, a new feature for Mac OS X 10.7 Lion. Mission Control combines some features of Spaces and Expose and creates a new interface in Mac OS X for navigating between apps. You can give apps their own screen and flip between screens easily.