Although they often seem to scratch in a breeze, CDs and DVDs are actually surprisingly resilient. Almost any disc that has merely been scratched can be repaired, since the data remains intact. If you want to destroy a CD or DVD, scratching it isn't enough: you need to puncture the data layer sandwiched between the outer label and the reflective surface of the disc face. Pro tip: almost any disc that, when held up to a lamp, does not allow light to shine through can be fixed.
For paranoids, that means taking a key to their old burnt disc isn't enough. The Sanyo Claw Destroyer promises to destroy any CD or DVD permanently. It works by punching hundreds of little holes in the surface of the disc (with a noise level similar to an electric pencil sharpener), as opposed to my first delightful guess: a shredder that spits out a compact disc confetti of razor shards from its back-end.