David asked if Drobo is cool. →
It looks interesting, but their site is remarkably light on information. From poking around, I found that it costs $699 empty, and you can add up to 4 SATA hard drives to it. It does some sort of RAID-5-like replication at a higher level (not at the drive-block level), effectively giving you [total - 1 drive] capacity. You can only lose 1 drive at a time and keep your data.
It only mounts via USB, and while you can move it between hosts, it uses NTFS for Windows and HFS for OS X (depending on which OS it’s set up with) so you can’t have full read/write access between a PC and a Mac.
It seems like a very overpriced, over-marketed device that might offer some usefulness to a few rich nerds, but probably isn’t worth the immense cost premium over a better, faster, more resilient, better-supported standard RAID setup of similar capacity.