We have a nice particle system when it comes to emitters, but I can't think of an easy way or any way to attract or repel particles. I was looking at TV3D 6.5, and they have a particle feature called an attractor. It can be used to influence particles by either attracting them to this special entity or just the opposite by repelling them. It seems to be a helper object given it depends on the presence of an emitter.

They also have a keyframe feature for emitters which will allow certain events to take place at a pre-determined time during an emitter or particle's lifetime. This would be another cool feature.