Yesterday I found AjaxRain - Great collection with 600+ Ajax or Javascript code snipets and examples.
I like that site from the first look, because everything in it is clean, neat and usefull. I really like sites having visible preview of the functionality as well as direct link to the example - it just show you the code in action. Everyday there are few new snippets/examples so I think this is one of the good sources for Ajax or Javascript expiration.