Not to just join the chorus, but I am blown away by Google Suggest. It's a simple idea, but well executed - it guesses what you are searching for as you type it and presents the options as a list. If you've used the auto-complete feature in IE, you'll get the picture.
\ Suuure... This is what you were *really* searching for.
So in the above screenshot, I've typed in "good clean f" and Google has presented it's best guess in the text box as well as other options below.