This is by far the most useful site ever. In the last month I have visited it every day. Its a pleasure to read, is full of accurate information for JavaScript programmers. When I say “most useful site ever” I really really mean it. If you are writing cross browser JavaScript, this site has all the differences laid out in easy to read tables, code examples and workarounds.

“QuirksMode.org is the personal and professional site of Peter-Paul Koch, freelance web developer in Amsterdam, the Netherlands. It contains more than 150 pages with CSS and JavaScript tips and tricks, and is one of the best sources on the WWW for studying and defeating browser incompatibilities.
It is free of charge and ads, and largely free of copyrights.”

http://www.quirksmode.org/