I've always been interested in 3D modelling, animation and graphics software. Once in a while, I look around the net to find something to play with.
Check out the demo of particleIllusion. Wicked, as they say. It's a standalone particle effects application. You can see examples of what it can do on the main web page. These effects can be composited into video but I haven't tried it yet. Best of all, it seems to run fine on modest hardware.
There are more resources on using particleIllusion over at shockingtales including a fantastic tutorial on adding a lightsabre to a video. Of course, all kind of idea's spring to mind about how to spruce up family video's. Could turn those water pistols into ray guns!
A competitor to particleIllusion is combustion by Discreet. They also have a free trial download.