compositing practice materials

can anyone suggest somewhere i could download materials so i can practice my compositing?

I have been learning Shake and after working through Marco Paolini's excellent book find i need more stuff to further my knowledge. Unfortunately, nothing we do at work is suitable and i don't know anyone who does 3d rendering. Its been suggested i try Maya PLE but I don't have the time or inclination to learn something else as well - as a newbie it would more than likely be crap and not suitable for learning compositing with anyway.

Its a bit of a catch22 trying to find such material, and i'm hoping someone might be able to help.

thanks in advance

adam

"silly keeps you sane"