A fun little time waster, found via Download Squad

Pulsus game

Drag the dots to the screen to repel particles. You want the "sinks" to fill up with particles before "source" is all out of them.

Colored dots attract like-colored particles and repel all the rest. Colored sinks attract all the particles, but only like-colored particles help them fill - the rest lower their meter.

There's 20-some levels, only a couple really challenging ones, but fun all-around.