I picked this device up for about $90, and quickly flashed the firmware with Unslung, which basically means I have my own cheap little linux box now. You can read more here:
So far I have my Slug doing the following:
- pc’s and macs in the house rsync to it on a daily basis to back up all important files
- I have the primary drive mirror to the secondary drive on a nightly basis
- I run an FTP server on it for some docs, so I can get to them from wherever
- I run OpenSSH on it, so I can access it from wherever.
- I run an mt-daapd server on it, which is an “iTunes” server. Basically anyone that runs iTunes in my house on my subnet will see the “Slug Music” server in the list of shared libraries.
- I run both SMB and NFS on it so the devices can mount it directly, not just via rsync.
There’s a lot more that it can do — bascially just about anything a linux box can do. The Unslung version is based on the Linksys firmware and has about 500-600 packages built for it, though I found that most take some tweaking to get to work right. I was tempted to do a debian install, but they don’t have a binary flash pre-built — you have to build your own. And that’s more work than I was interested in taking on right now! At 1st I was tempted to move more to it, such as my web server, or at least portions of it, but I’ve decided to use a real server for that kind of thing, at a real colo. š
2sparrows 
That’s AWESOME!!! So you got all that set up the right way now eh? What was the hardest to configure? The SLUG is acting as the RSYNC server and the other devices are RSYNC clients? Very COOL! I’ll be picking your brain for config tips later.
The hardest part was getting permissions correct between the windows boxes, rsync, and the ftp server. Windows tends to chop off most of the bits of the unix permissions, and having a linux box allow ftp to get files w/o the right permissions is tough (impossible?). I tried all sorts of things including forcing the umask of rsync, chmod -R on the directories, changing the options on the rsync command, etc. What is really bad is I can’t remember right now what I did to get it all to work, since I went through so many iterations. I’m sure i can figure it out if/when you need the info.
The other thing that was hard was getting passive ftp to work. The slug sits behind a firewall, and I had port forwarding for 21 and 45000 – 45100 set, and then set proftpd to use 45000-45100 to be the only passive ports it would use. It would work for a few transactions per session, and then fail. When I put the slug on the dmz it worked fine, or if I turned off passive on the ftp client it worked fine. I finally changed the passive ports from 45000 – 100 to some other range on both the ftp daemon and the firewall, and it started working.
The slug is the rsync server (daemon).