Not quite easily affordable in comparison to the NSLU I don't believe,
but I can safely and strongly recommend the Infrant ReadyNAS NV+ for
tasks like this. Ordered one myself not to long ago, threw 4 500 Gig
HDs in it and have slowly been filling it up. Supports SMB, NFS, AFP,
HTTP and FTP transfers, email alerts, a few add on server
functionalities I don't really use cause it is easier just to net mount
NFS, etc.
It has its own 'config' program, but I just go to the admin page
manually and log in with no problems from Linux.
Seablade
Not a vendor for this, I promise, just pretty happy with it.