The synology stuff also comes with an iOS app which allows browsing (and background streaming) directly from your NAS box. Unexpected but rather nice, though if it'd transcode my stuff from FLAC that'd be *really* useful

I have a tiny DS411slim, very happy with it. 4x1TB 2.5" disks, takes almost no power and is almost totally silent too.

Also, they actually offer a shell as a standard feature, and when you apply updates (painless), it doesn't blow your stuff away either.