This is a great idea, and will certainly be added to my bookmarks.  From the project homepage:

Google Doctype is an open encyclopedia and reference library. Written by web developers, for web developers. It includes articles on web security, JavaScript DOM manipulation, CSS tips and tricks, and more. The reference section includes a growing library of test cases for checking cross-browser and cross-platform compatibility.

Google Doctype is 100% open.

• Open source
• Open content
• Open to contributions from anyone

The encyclopedia can be found here…

Mark Pilgram explains Google Doctype: