Have you forgotten a password to a website, email account, or other password? If you use Mac OS X's Keychain, chances are that your password can be easily retrieved.
First off, open Keychain Access.app (located in /Applications/Utilities/). Once there, scroll through the list of keys until you find the one that you're looking for. Double click on it and check the box that says, "Show Password." Once you authenticate with your user credentials, your forgotten password will be displayed in the text box.
Want more tips and tricks like this? Visit TUAW's Mac 101 section.