Hi
I am going to use STK in my masters thesis, by implementing neurofeedback functionality in the game, using VRPN as a bridge. This may be a bit of a special area, but I thought that some people could find it interesting. Maybe the VRPN support can be used for something else later as well, as it supports a bunch of other devices such as the kinect. (If I end up fixing bugs or similar while I am at it, I will of course submit patches and/or give feedback.)
I am working on a git clone here: https://gitorious.org/stk-neuro/stk-neuro. This will of course be GPLed as required, though if there are any licensing issues I should be aware of, please let me know.