Brando's one-to-one hard-drive duplicator looks like the kind of thing that, while you only need it every now and again, when you need it, you're incredibly grateful to have it. Plug a full hard-drive into one end, an empty one into the other, and copy away at blazing speeds (they claim an average of 95MBs for SATA-to-SATA copies). It can copy over the partition table as well — also, it'll diff two drives, do secure erasure, and do integrity checking.
Century KD25/35PRO HDD Duplicator
(via Red Ferret)