Spireng is a (yet another and very simple) HTML5/Canvas 2D engine.
Features (very basic):
* Drawing
* Sprites (with rotation)
* Sprite animations (based on sprite sheets)
* Resource loader
* Sprite layers
* Handles resizing of the drawing area (browser). (Note: It always covers the full browser window by design)
It forms the basis of another pet-project of mine, not yet published.
For the time being I'd not recommend anyone else to write anything against it as it's extremely immature and the API is very likely to change.
It might however be of some interest for HTML5/Canvas beginners that want ideas on where to start and quickly get some 2D stuff up and running.