After a lot of research, I finally found a NAS system I might feel comfortable with. I once owned the Linksys NSLU2, but 3 power supplies, drives that can’t spin down when idle and no RAID just didn’t cut it.
This overview about network performance of various drives is a great place to start if you’re looking for a NAS. I started looking into the D-Link DND-323, which seems to be everybody’s darling, and almost bought it.
The Zyxel NSA-220, however, holds the promise of a geek firmware: it already features a bittorrent client, and it also plays well with iTunes.
More details when I had the opportunity to play with it for a while.