I’ll proudly admit that I’m way too lazy to actually code up a DHTML auto-complete control like this one. It’s just that I have better things to do with my time. Don’t make fun of me, I do! Okay, maybe I don’t but this is still a nice auto-complete control 
Who needs Ajax when you’ve got perfectly good Javascript arrays 
The Code Project – Auto-complete Control – JavaScript
Using the JavaScript regexp() object, the script will run through the array containing the keywords and match them one by one. After which, a DIV will be created dynamically using document.createElement(). Finally, when the user presses the ‘Enter’ key, the DIV will be detached and the input box updated.