when weather allows, i commute on my road bike with its 700x23 tires inflated to ~130psi. it's not so much for the speed, i just like the sensation of a really high-pressure tire. it makes me feel like i'm riding on steel wheels, no rolling resistance at all (i also haven't had a flat since moving over to my road bike for commuting, knock on wood). however, tires that narrow and high-pressure really aren't the safest bet when roads are wet, so i have a hybrid that came with some 700x37 tires. they're pretty nice tires, but i can feel the extra weight, and their max inflation is only 85psi, so i think i might drop down to a 32 or 28 with a slightly higher max pressure when it comes time to replace them.