I have become a major fan of jQuery, so the docs for it have found a place on my bookmark bar as well.
Finally, I sometimes find that the Microsoft documentation for IE is helpful. They often reorganize their site, and their search isn't very helpful, so the best way I've found to find information is to use google search with the term
site:msdn.microsoft.com in addition to your search term(s). I don't know how anyone at Microsoft finds things on their own site, but I expect they end up using Google too.