Armed with a Sandy Bridge-based Celeron CPU, QNAP's TS-470 handles the traffic from four gigabit Ethernet connections. Or, with the addition of a 10 GbE upgrade card, it can be made to push well over 1 GB/s, providing you use the right storage.
Are you looking for an entry-level NAS system and don't have the spare parts to roll your own? Buffalo's LinkStation 420 uses a fairly basic platform, and we have a few critiques, but it's otherwise a simple and affordable storage solution for the home.
D-Link's latest NAS comes with a built-in web file server and a secure FTP server to provide file access over the Internet.