Axis is a free open source 3D engine for web pages and desktop applications. It's been a month since its official release with full source code, editor and all and there is more content available now like samples, info pages, API documentation and recently the team opened the discussion pages on the site where anyone can get help.
From the team:
We are a micro team, who view software as an art and who believe art should be free and unrestricted for everyone. Thus we grant our work free and aim to improve it in the best possible way - by interacting with developers and adapting it to their specific need.
Check out the latestaddition, a small 80-lines-of-code prototype of a space flyer game, playable on the web at http://palitri.com/axis/showcase/#Space
You can learn more at http://palitri.com.