Does this exist?

I was thinking that a cool product idea would be an external hard disk housing that connected to the computer via Firewire (400 & 800) and USB (1 & 2) (and maybe even Ethernet?) and inside had a Serial ATA bus and did hardware RAID. So I could have this portable little RAID box that I could bring to different computers as necessary, not having to worry about setting up RAID on each machine, etc. It’d be great to just have a couple hundred gigs lying around that I could access reasonably fast but that was also “safe”.