Rotoscoping is where you take film, and apply image processing to make it look like an animation. Movies like 'Waking Life' and 'A Scanner Darkly' used expensive rotoscoping techniques (plus oodles of animators to polish it). I've added a tutorial about how to do rotoscoping yourself using flash and photoshop.
Enjoy, and post links to your rotoscoped movies!

Check out the rotoscoping tutorial here