Not only a great idea but also free load testing for the playcanvas.com guys. Their appserver appears to have melted: the CTO's hands are currently a blur on his keyboard!
Clickable: http://www.mixamo.com/editor/new/1643
We're reworking the animation system in Three.js, so soon you'll be able to make your animations in Mixamo, and deliver them on the web. You can do it yourself with Three.js, or with our help using http://studio.verold.com (though, if you're going to do another Gangnam style, please use a better remix - like https://soundcloud.com/stirling-inch/pretty-gangnam-fly-stir...)