Google has recently released a new project called DocType.  Their plan is to create the "Everything Else"DN, a more cross-platform web development encyclopedia per se.   As stated in the introduction video, MSDN is great for developing for the Microsoft-centric platforms - but really falls short with cross platform information.  Their goal is to get the web development community updating and adding to this resource over time.

This is of particular interest to me.  Now that I can no longer hide behind 'Mapguide 6.x needs an ActiveX, so IE is my only supported browser'. =)

In addition to a bunch of great HOWTO's, and reference documents - they're also releasing a good chunk of the javascript used by the Google applications - in an un-obfuscated state and with comments.  The entire library can be downloaded from the SVN repository and stored locally for faster, or offline access.