Three.js has OBJ support natively (I've written a extension to allow you to view them directily on your github[1]). COLLADA and glTF, which provide support for animations, are also supported[2].
Cannon.js is a promising physics engine[3].
Nonetheless, it is exciting to see Microsoft not only supporting WebGL, but also promiting open source libraries to ease development on the platform.
I tend to be dismissive of OBJ support since it's so easy to do and doesn't get you terribly far, but yes that's nice.
Collada support is a lot more impressive, but FBX support -- even though FBX is proprietary -- is much more useful given the wider and broader support for FBX out there (even Blender can export to FBX).
Cannon.js is a promising physics engine[3].
Nonetheless, it is exciting to see Microsoft not only supporting WebGL, but also promiting open source libraries to ease development on the platform.
[1] https://github.com/danielribeiro/three-hub
[2] http://threejs.org/examples/webgl_loader_collada.html
[3] http://cannonjs.org/