Diceware
„This page offers a better way to create a strong, yet easy to remember passphrase for use with encryption and security programs. Weak passwords and passphrases are one of the most common flaws in computer security. Take a few minutes and learn how to do it right. The information presented here can be used by anyone.”
This is cite from original home page of Diceware Passphrase: http://world.std.com/~reinhold/diceware.html