IMVU uses a lot of open source software on both our client software and the web site (frontend and backend). One of the packages we use is Cal3D, a 3D skeletal animation system. We’ve made a few changes to Cal3D over the last year or two, including support for morph targets, exporter UI improvements, an improved animation scheduler, vertex colors, and others. In the past, we’ve published our changes directly back to the Cal3D project, but this wasn’t strictly in accordance with the LGPL, under which Cal3D is licensed. So now you can easily download our version of Cal3D directly from our technology page!