Emitting sparks or dust at rigid body collisions I'd like to have automatic particle emission when rigid body objects collide with others (I have many objects). Not that I can find it but I've read of an option under children that can spawn others when a particle collides, however I haven't seen anything regarding rigid body collision events.

Can this be done out of the box? With a plugin? Or, last resort, with a small amount of scripting?
This is not yet possible. However, this is one of the many great things Particle Nodes will allow - these are still in development but can be tested here.