Yep, just loaded it up with another 1000G to make it 2TB total. It pretty much does everything. I use it as a FTP drop spot for clients but it can do much more.
I have a 1TB for personal use (movies, music, pictures, etc) and another TB as kind of an off site studio backup.
Another option is a NSLU2. I had one before the Qnap and it works well if you don't need the extra features. Can be found on ebay for cheap.
You can get cheaper D-Link ones and put your own drives in it. Drobo is cool because you can swap drives and the drives don't have to be the same size, but it's expensive.