Everyone eventually forgets a password or two. It's OK, don't be ashamed. Even your friends at TUAW have committed this error. Honestly.
Ivan at CreativeBits offers a simple way to reveal a forgotten password with Mac OS X's Keychain Access application. You'll find it in your Utilities folder (which lives in the Applications folder). It lists all the passwords you've stored for different applications (wireless networks, FTP servers, etc.). Just select the one you're interested in and perform a "Get Info" by hitting Command-I. Good luck, and write it down this time, will you?