HEAVY EXPANDED MOBILE TACTICAL TRUCK (HEMTT): Via the Federation of American Scientists, I give you the HEMTT. These bad boys are the workhorses of the US Army, which uses its 16,000 HEMTTs to keep our armor and infantry divisions supplied with fuel, ammunition, food, and other essentials while they're operationally deployed (as they are now in Iraq). Each truck can be configured to carry fuel (up to 2500 gallons) or other cargo (16.5+ tons), or to serve as a tractor or a wreaker. They've got winches and cranes and all sorts of nifty devices, standard!
But what if you need to move something really big, like a 70 ton M1 Abrams Main Battle Tank? Then I guess you'll need to upgrade to one of these.