I frequently scrap hard drives for metal recovery. The controller boards have a lot of precious metal on them, so I sell them to a company called Boardsort (http://www.boardsort.com). The rest of the drive is mostly aluminum, so that ends up going to the scrap yard. The outer shell is cast aluminum. The platters are either aluminum or glass with the chrome plating with trace amounts of precious metals. The read/write head has a copper or copper plated winding on it, so I toss it with my electric motors along with the drive spindle. The magnets inside I may keep or give to someone who I know collects them.

a Beowulf cluster of these?

To me, the owner of any electronic device that is password protected should not disclose the password to the device unless the authority has a warrant out for that person.

What about
Urassis, Grass & I. M. DeLawnmower

What I would do is configure a laptop to run DRBL or Windows Deployment Services (WDS). Both will give you PXE boot options and can boot whatever Linux (DRBL) or WinPE (WDS) utilities you want to use. WDS is a part of Windows Server 2008 R2 and for what you are going to need it for, you shouldn't have to purchase a license since the evaluation period should be sufficient time for you to complete your process. My suggestion would be to customize a Windows PE image to run a backup utility to capture all the data and write it to wherever you are putting it at, then run Gdisk32, which is a part of Norton Ghost to wipe the drive once the backup is complete and verified. You should be able to script this so it runs automatically once the PXE boot completes off a WDS server. I'm sure there's a way to do the same thing with DBAN if you're going to use DRBL instead.