This Hammer (don't...) Storage myshare NAS seems to be one of the few home and small business units to offer up to 2TB of storage. The unit itself takes 2 hard disks to form anywhere between 320GB and 2TB of storage, with an extra USB expansion port in the back for printers or even more space. Best of all, the NAS has Gigabit Ethernet and RAID 0/1 support, so the performance will be (theoretically) pretty solid.
The 1TB version is on sale now for $499, and the 2TB will be shipping in August. We're always looking for more storage for all the crap we amass from being on the Internet 18 hours a day (we went on a Batman comic downloading spree last week).