Out of the 5 in total, my main 2 computers are on separate networks: one for VPN to work (my email), and one directly attached to the ADSL router for my wife's personal email and browsing. The problem is that the PC's cannot see each other since they are in different networks, yet they stand two metres apart and I wanted to share my printer and scanner for the other PC to benefit.
This morning I bought a 4.5m FireWire 6-6 cable for 25 in order to connect the two PC's back-to-back using the firewire ports. The setup was very easy: assign a static IP address each from RFC1918, and the link was useable just after that at 400Mbits/s. The joy of copying files at OC-3 speed at home is great =)
Anyone else has tried this yet ? If not, and if you ever need a quick, cheap, reliable and easy to setup networking solution for a couple of PC's, think about it. These guys have thought about it for quite some time, it seems.
Update 13 May: Someone posted Apple: IP over Firewire Updated.