We found this great little device which now acts as a file server on one of our networks.  It’s not just a networked USB disk though.  Disks can be configured as RAID (Mirrored or Striped) or JBOD (we couldn’t really see the point of that). 

It’s also got a USB port for sharing a printer (only a printer unfortunately, but we’re sure there’ll be a hack sometime soon), an iTunes Server, FTP server and a fairly easy to use web interface.  Add to that a Kensington security slot to try to prevent removal by light fingered potential owners.  All in all not bad for a touch over £100.