I'm also a huge fan of MDN. Fun fact, if you use Duck Duck Go you can add "!mdn" to constrain your search to just MDN. It's now my #1 way of searching for HTML tag properties and CSS syntax.
You can do that with Firefox's bookmarks (last I looked) and Chrome's "search engines" (and there's probably something in Opera or Safari) using any URL you want, %s in the URL will be replaced with your search.
