What's in a Typical Geek Home Network?

Mike D asks: "I have several machines on my home network (A Mac OS X server, a few Windows XP desktops, a G4 workstation, etc.) as well as various devices (wireless base stations, VPN/firewall) and always have spare machines around that I'm torn on what to do with. So, I wonder -- what do 'typical geeks' have on their home networks? What items do you feel are a requirement, what are luxuries, and what is just cool stuff that I should integrate into my own network? Of course, suggestions should be cheap/free/use existing hardware I can find around the house."