If you let them catch up, you can make a sort of pink torus around the mouse.

I feel like a god creating the universe, really nice effects!

If you move it steady in a vertical line it creates two lines that looks like they were smashing against each other.

I actually think this could become a game; maybe you show the player a pattern and then he tries to recreate it... or something among those lines.

There is already such a game, kind of:

http://www.ea.com/auditorium-iphone

Some of the levels are pretty hard!