Bullet forums maybe? (they're mostly dead lately though): http://bulletphysics.org/Bullet/phpBB3/viewforum.php?f=4
I really like this project/idea
I've been barely visiting Bullet forums, because I have been working on control for robotics and articulated characters for a few years now, and now getting involved with deep learning in this context (I work in the Google Brain team nowadays where we create/use TensorFlow). I just replied:
I'm going to add some more motor control and deep learning demos in Bullet for the upcoming release.