Love love love my Topeak Road Morph.

http://www.rei.com/product/4684369.htm

It turns into a floor pump with a foot thing and a gauge, so you can push into the ground instead of hanging on to the pump and trying to use only upper body strength to fill the tire. I'm somewhat of an expert at fixing flats on the road, since I've had at least a dozen this season. I can fill a tire to 100 lb with the Road Morph, and I was lucky to get 50 with my other pumps. Also helps avoid breaking off valve stems, since it's got a flexible tube that connects to the valve.