A collaboration between major web companies and the World Wide Web Consortium (W3C) has resulted in a new community-driven site, Web Platform Docs, providing a one stop wiki for Open Web Platform (HTML5, CSS, etc.) developers.
W3C along with the Web Platform Stewards, who are currently Adobe, Apple, Facebook, Google, HP, Microsoft, Mozilla, Nokia, and Opera, have launched this effort to centralize web practices in a wiki and preserved to foster sharing and reuse.
The site will include best practices for feature usage (including syntax and examples), cross-platform interoperability, standardization status of specifications, and feature stability and implementation status. Each section, in true wiki style, can be rated and links back to original sources. The site appears very much in the developmental stage at this time of launch.
The site also features a section for beginners, so this resource appears targeted at developers of all knowledge stages.
Anxious to get going? Here is the getting started page