A recent discussion thread on the WeldingWeb concerned photos that someone dug up of a truck that was outfitted for welding. The truck is in a junkyard and certainly out of service, but it's quite a site.

Equipped with several generators, an air compressor, a control panel that put out 120V power, a yellow spotlight and a siren up front, the truck must have been an impressive rig when it was in use.

You can find photos of the old rig at http://weldingweb.com/showthread.php?t=23328.