I run a DNS and webserver. There'll be four of us geeks living in this house this year, and all of us have two or more computers (and monitors) each. So I'm spending a lot of time installing Cat5 cable to each room, including the living room (where we'll have one hell of an entertainment system). Of course, laying cable without doing anything permanent to the walls is awkward, but easily solved with cable ties and sticky pads.
Cable ties: the duct tape alternative.
The main reason I run a webserver: I want to.
The main reason I run a DNS: I have a domain and our network has five real IPs, so I'm gathering some experience by configuring a BIND nameserver. Next step is a mail server.
Also running on that server is a complicated DHCP arrangement to let us run two seperate networks (one real, one on a local subnet only) on the same switch behind the same router, and bind the real IPs to certain MAC addresses.
When I reconfigure my Duron 1200 system to replace the existing server, I'll set up a dedicated Descent 3 server too.
I always put computer performance before appearance, but I've decided that just for once I'm going to have a computer that looks like a beast. When I first took my Athlon64 machine to a LAN party, it was in a dull beige case. Someone was sniggering as they asked me what the spec was; I just pointed to the A64 sticker.
IIRC, it was the only A64 there.
Next time, they're gonna know it's a powerhouse. What they won't be expecting is two computers in the same case...