Superflow MV50 is highly popular with a lot of guys. Cheap, and pushes a good volume of air. Most cheapie compressors will inflate to 125+ psi, but take FOREVER to fill a tire. The MV50 has a decent sized piston, so it won't reach as high of pressure, but moves more volume.
This compressor is packaged under several different brands and part numbers. Mine was "Master Flow Tsunami MF-1050", exact same compressor. I just saw one the other day, I think it was at Walmart, but I can't remember exactly.
Here's a review
http://www.parksoffroad.com/prodrevi.../mv50/mv50.htm
Here's some mods
http://www.jeepforum.com/forum/f46/s...al-air-396001/
I modified mine as well. Put a 60 psi gauge on it for a little more accuracy, and also changed the fitting for a quick connect and standard hose. Used a tire chuck that clamps on.
Mine would fill a 33x10.50 on a 8" wide wheel from 10 psi to 24 psi in a little over 2 minutes. Not fast, but a heck of a lot faster than the cigirette lighter powered compressors are.