Having recently purchased the Linksys NSLU2 (commonly called a SLUG) for use in a hacked form as a low power home server, I've been playing around with it a little to customise it towards my needs. The eventual aim is to run SqueezeCenter on it to power my new SqueezeBox Duet. The most commonly used hacked version of Linux provided by the SLUG hacking community is known as uSLUnG, hence hacking the SLUG with this being called unslinging.
The process of unslinging is made very simple, thanks to the great instructions developed over the years by the community, and with such a large community the amount of testing on these instructions is pretty complete too. First step is to download the firmware binaries as described on the SLUG Firmware site. I used firware version 6.10 Beta which is considered the latest stable version in spite of having a beta tag. Then simply followed the instructions in this README file and I was done. The whole process takes no more than 10 minutes or so.
Now I have a nice little low power Linux box sitting on my network raring to run some services for me. Pretty much anything you can think of has been done on the SLUG, Apache, MySQL, etc, etc, etc. So the list and choice of what to do is very complete. For now though, I've just installed a few basic utilities (coreutils), Perl (I know I'll need that later), GCC, and SSH for remote access.
I'll quickly mention the SLUG specs in passing too. It has a 266Mhz ARM based Intel XScale processor, some of the early models were under clocked at 133Mhz but all the recent editions run at full speed; 8MB flash; 32MB RAM; 2 USB 2.0; 10/100 Ethernet; runs from 5V DC power and measures just 2 x 9 x 13cm. With one USB disk attached my Current Cost meter reads it at about 5 watts power usage which I guess may rise a watt or two under load.