Currently using 3 different old hardware boxes. One each for:
1. Test machine - meant to be built, played with, broken and rebuilt ad nauseum.
Currently running Debian Etch
2. File server - serves up files to my local network. Currently running Debian Sarge
3. Firewall - Don't have this one up and running yet. I have tried unsuccessfully in the past to get IPCop running on this box, but won't give up just yet. Will give it another shot soon.