I also hve the Porter Cable C-2002 Pancake unit as mentioned above by others. While I have on-board air, I hate running the engine (at $3.50 a gallon now) just to air up my tires.
Mine will got to almost 145, while it's advertised to 150 and it builds pressure pretty fast. I don't always haul it on a trip, depends on the circumstances, but I always take my air hose and chuck.
How is it one careless match can start a forest fire, but it takes a whole box to start a campfire?
Dan & Linda, 2008 Camelot PDQ, 2008 Jeep Wrangler