My local PC shop has a hard-drive destroyer for people who are concerned about data retention. It's basically a shaped anvil plus a punch with a massive lever (

My local PC shop has a hard-drive destroyer for people who are concerned about data retention. It's basically a shaped anvil plus a punch with a massive lever (four feet long) that gives you enough mechanical advantage to break open the drive's metal case. Great fun to use, although probably not as satisfying as destroying a printer.