A friend of mine has one of these:
http://www.synology.com/products/pro...12%2B&lang=enu
He has 15Tb of disks in it and with 2 drive redundancy he has 9Tb usable. It's very quiet and very power efficient and has an excellent web interface so you can administer it from a browser locally or via the net. It's upgradeable and expandable so I would see it as a relatively long term solution.
It's on my list... after a bunch of scope related stuff
