This is the DTV Shredder
, a militarized skateboard with two caterpillar tracks. It can travel at over 30mph, go up 40-degree slopes, turn around in four feet, and be remotely operated. It's also quite spectacular in action:
and some pictures:
According to the manufacturer, it can handle any kind of terrain and its low center of gravity makes it "ideal for reconnaissance, rescue/recovery, mobile surveillance, and medical evacuation operations".