I put a Redshift Shockstop stem on my road bike:
Redshift Shockstop Stem. It does work to absorb the shock in the hands and arms without feeling like you're riding with a spring, which it isn't. Of course when I did a quick review here the response I got was to lower the pressure in my tires instead. I tried that first but I don't like the feel of squishy tires, plus in NYC you'll get pinch flats. I usually run my tires at about 5psi under max, and for GP4000/GP5000 I run at 110psi in a 700/23 size.