If you have central heating see where the pipes go from downstairs to upstairs

Heh, I forgot that I do this in my house now. My cable modem and server sit in the basement, and I run a Cat5 cable up into the exposed pipework of the house. It then eventually dusappears into a vent, and reappears in the bathroom, where it hides under the rug, and goes into the hub in the next room.

Works rather well, and the response from someone who notices the Cat 5 under the rug is always fun