Sunlite's Series II Chain Tool works with Shimano IG, HG, and UG chains. The vinyl coated handles make chain maintenance a breeze, and the screw style makes loosening up a stiff link easy.
Be prepared out there with Sunlite's 8 Function Multi Tool. You've got 2, 2.5, 3, 4, 5 and 6mm Allen wrenches as well as a flat and Phillips screwdriver. It's small, it's light and it doesn't take up much room.