Watching The Gadget Show at silly-o'clock the other night and they featured a program called FX Home, which is a cheap but effective special effects program.
I've only downloaded the free demo at the moment but I've got to say, for £89 for the EffectsLab Pro package, it's pretty darn impressive.
Even managed to do some cool light saber effects, only took 10 mitues to make it look somewhat passable.
So any of you film makers out there, wanting to add effects and green screen - check it out
(Will try to post some clips soon )