QuickSilver

QuickSilver is an amazing tool for OS X. It combines power of command line with beautiful OS X user interface and adds its own clever and subtle magic.

QuickSilver - A Better OS X In Just 10 Minutes
http://vjarmy.com/archives/2004/03/quicksilver_a_b.php

Quicksilver: From A Better OS X To Even More
http://vjarmy.com/archives/2005/02/quicksilver_fro.php

QuickSilver Keychain Plugin
http://www.liquidx.net/keychainmodule
UPDATE (Dec 03, 2006): This can be done better with 1Passwd

43 Folders: Quicksilver: moving around and training yourself
http://www.43folders.com/2004/09/quicksilver_mov.html