Making pavements more permeable is a major step towards greening cities. Permeable pavements let water soak into the soil, reducing run-off and recharging aquifers. Here's a pretty decent overview of the kinds of solutions now available
It is indeed a good overview, though I'd say it leaves out the best product in the market: Resinpave, http://www.schommer-sons.com/resinpave.htm, which is a non-concrete binder for normal aggregate, made mostly from pitch and rosin from pine trees. It's about twice as expensive as concrete, but it's also about twice as strong, so price is about the same and you use less mass; plus it's porous. I'm pretty sure it was used for paths & parking lots in Chicago's Center for Green Technology, the first LEED Platinum building.