A few years back a guy built a custom portable computer who's sole purpose in life was to crack wpa passwords. They called it the Janus project. A few of us on the Netstumbler forums though it was a cool project so we made our own versions of it. Mine started out as a mini-itx based computer, but I soon found that it didn't have enough horsepower, and has gone through several hardware updates. It's currently a Pentium 4 running at 2.6Ghz. At the time of it's creation it had 4 Atheros based WiFi cards, but I gave two of them to Renderman for some project he was working on. It was supposed to be able to be run completely from a 12 volt DC source, like a car, but at the time I built it, the price of the display would have cost twice the amount of all the other hardware combined. The current build is running Ubuntu 10.04 with an encrypted drive. It also has a BackTrack 4 drive as well. Eventually I'd like to rebuild it with a smaller usb powered display, a newer core2 based mini-itx board and substitute the mini-pci WiFi cards for a bunch of usb WiFi adapters.
This is an older shot of the inside. You can see two of the WiFi cards on the 4 port mini-pci riser.
Here are the 8 RP-TNC connectors. I chose them because I had the antennas already from WRT-54g's.
This is mostly how it looks today. Everything can fit in the case with the lid closed, handy for transportation.