I recently had a WD-80G hard drive (from Aug'01) die in my brother's Cube. He was complaining of "weird" things happening -- ultimately his entire iTunes library was scattered through the "Rescued Items" directory, but salvageable. Prior to Disk Warrior his drive was failing the S.M.A.R.T. test (which via Disk Warrior is turned on to always check) and nothing else would touch the drive.

Disk Warrior not only rebuilt the directory structure it allowed the drive to mount for a backup/copy -- something Disk Utility or Drive 10 couldn't do. It took almost two days to rebuild the directory structure, but another 2 to actually copy the files (and two more to restore everything for him :). Best $$$ ever spent IMHO. His too... :)

It now monitors my IDE RAID-1 [SMART] on my PowerMac as well (other utilities take care of the SCSI-160 end :).