in long long ago 2009 I had that little project with a multitouch-table, which I think might be worth sharing. Actually it handles the problem making a so called graph planar.
Don't run... it's a math problem! But its fun!
On the project blog you can find valueable information (in German, sorry) about the project, what tools were used and how the lightning was setup up.
You can actually download it (for free) from the Android Market if you have a supersized multitouch table to call your own: