^^^^ You "go get 'em" into little orbits if you can, so you score 300 per frame instead of 1 per frame.

Captain_404, you might want to have a look at this, it's a similar idea except the 'enemies' get removed if they collide or if you can get them into a circular orbit for a few seconds.

http://www.evilbastard.org/slight/gravity2s.swf

If there is one thing I would change with your game is to make it move faster with mouse control. The way it is now, to do small fast movements you have to hold the button down and do large sweeps that are usually off stage. It would be better if you made it move much faster towards the mouse, but capped the maximum speed.