Angry Birds is a puzzle video game developed by Finland-based Rovio Mobile. Recently it has been ported for web browsers. The implementation uses WebGL for rendering the graphics.
Most of the WebGL demos so far has demonstrated the 3D possibilities of WebGL but the WebGL version of Angry Birds shows how well WebGL can be used for 2D content as well. Another fine example of using 2D on WebGL is a nice space shooter game called X-Type http://www.phoboslab.org/xtype/, which uses WebGL-2D, a library that implements Canvas2D API on WebGL context. https://github.com/corbanbrook/webgl-2d