I have a Seagate Travan 40 (STT3401A-RD) working on a file server running RedHat 7.3. The back-up software that came with the unit (Tapeware) actually worked right out the the box with no fiddling around. The Linux documentation that came with it was suprisingly good.
As aixmurderer pointed out, it still is about 2.5 time the cost of another hard drive, but you can tape tapes off site.