I am a fan of Western Digital Hard Drives, but a fan of their External Drives. I keep hearing stories of their failure, but even though I have had a 500 GB WD External with no issues. Now they have came out with the My Book Mirror.
My Book Mirror is a dual-drive unit with Raid 1 for redundancy or Raid 0 for performance. You can get the 1TB model for $290 or the 2TB model for $550. If you run them in Raid 1 mode then the storage space is halfed, not Raid 1 with 2TB worth of space. The only bad part is that is USB only, but a really good feature is that the drives are replacable and there are no fans on this unit because the hard drive has low power consumption and so requires little cooling.
This is a good solution for people looking Raid back up in their setup. Drive space keeps getting cheaper and cheaper.
Link: Crave