Selectively turn off Lion’s “Resume” feature when opening an app

Lion introduced a new iOS-like Resume feature that allows apps to reopen with all documents, windows, and settings right where you left them. But if you want to override this setting on an app-by-app basis, simply hold the Shift key when starting an app. It will open to its native ‘clean slate,’ with none of the documents or windows you had open the last time you quit the app.