Since everyone else has started showing off their setups, I thought I'd throw my hat in the ring as well.
The battery in my laptop is buggered, and I rescued a pair of 12V, 12Ah batterys from a UPS a few weeks ago at work. Thought I'd wire em up to give my laptop some juice when I turned the Jackaroo off.
I've wired em into a project box from DSE, cost me a couple of bucks, with a cigarette lighter socket. At the moment, the wiring is straight thru from the external terminals which are connected to the cars cigarette lighter.
Plan is to rewire it to include a diode to prevent the "Auxilary" powering the vehicles accessories, and a fuse block to protect the sockets. Eventually it will be permently installed either under the passenger seat with only the project box visable for easy access, or the batteries under the bonnet.
Laptop is a Toshiba Satellite 1800 running XP Pro, with OziExplorer and GPSS (Just testing it, came with the GPS), with a GPS Mouse from TWIG Systems. GPS will be mounted in front of the windscreen between the wipers and cable feed through the firewall.