Stash-hole! A total compliment, of course.
There may be large magnets that can do the job, but I'm not sure how big they'd need to be. Cornell has a degouser (sp?)...it's big and actually heats the drives up so much that you have to wear heat protective mitts when you use it.
What we use in our office is KillDisk. http://www.killdisk.com/