I am currently working on a game for Avert. For that, I did some test on attraction/repulsion with Traer's physics library ( brilliant lib ), and obviously got carried away playing with lights and physics. The game is not going to be like that as it has to run online and on the largest panel of computers.
Basically this video is an excuse to try HD :)
Here are the online and downloadable versions, wich are more fun to use:
mightymess.com/repulsion