I got a pair of slick (treadless) tires for my bike. After some screwing around, I ended up with one in the front, and my regular, knobby, mountain bike tire in the back. It performed a lot better than it did with the knobby tire in front, and was much smoother with vibrations. I could really feel the water on the ground, and only had trouble when I turned too hard on a sandy patch. Otherwise, the one in front works wonderfully. I'm still going to change out the back one eventually, but after blowing a tube within 5 minutes of changing the tire, I'm still a bit leery. I got the el-cheapo slicks from Performance Bike - About $5 a piece. I know, I know...big spender. Works for me, though!
Hats off to Tom J., Darren G., and others at work who are starting bike commuting as well! Spread the word!