From the MAKE Blog, regarding shredders.
I recently blogged (HERE) about an industrial shredder I found online. Check out the demo videos–this thing tears right through a massive load of paper… and tree stumps, and oversize tires, and a couch, and a 55-gallon drum of hardened concrete…. and a boat… Somebody had WAY too much fun taking these videos. If you're looking for the single most over-the-top method for shredding paper, I think this is it.