I got a firewall router, it's a single floppy disk deal. (daschstien leaf firewall appliance). It has a mini http server for network monitoring, dhcp server, dns server, and does nat firewall for the rest of the network, therefore kinda a internet server for the rest of the network.
Other then that I have my main desktop, Slackware 9.0, I run a ftp server and a ssh server that I have the ports forward'd from the router. It is mostly for just personal convenience and a little bit for scripting/programming over the internet(intensely amaturish stuff mind you) when I get to a lull at work. Of course on that I got a X server/client dealy set up, but that's nothing special, it's just how X windows works.
I got a couple other junk computers I play around with, Got debian on 2 of them OpenBSD on a third, but right now they are in various states of unusability, just because I've been to busy to mess around with them lately.
At my part time job I have set up a old debian box to try my hand at integrating it into the windows domain their. Just mostly for testing, a proving ground so to say. It has samba, apache, ldap, ftp, webmin, nfs(currently disabled). Just to play around with mind you, it's a ancient 133 (still has the gigantic AT-style plug for the keyboard) with 48 megs dram (real screamer).