Here is my list :
:: OpenDP500 (daemon)
Media source for my DP558 mediaplayer http://www.kiss-technology.com/?p=558&v=users
:: Slimserver (perl daemon)
Media source for my Squeezebox http://www.slimdevices.com/
:: WWW
For various home projects http://xboxlinux.mine.nu
:: FTP
For various use (mostly used as a "drop off" for files when I'm on the run)
:: OSI server
For personal use on blogs and forums http://www.onlinestatus.org/
I would also like to run a ventrilo server - but my ISP doesn't really allow me to run any (!) servers - But they can't keep all ports blocked - so I'm still trying to get that to work..

Anyone else has something interesting running on their boxes?
Steinar T