It really depends on how wet you want it to be. Standing puddles are as reflective as mirrors. Damp pavement is only slightly reflective. You can try adding a 'puddles' layer to an existing material, then making it reflective and controlling the alpha and reflectance channel with a noise node. That should get you started.

Here are a few links to some renders I did using reflective ground treatments, maybe they can provide some inspiration:

[ http://www.renderosity.com/mod/gallery/index.php?image_id=1808082

](http://www.renderosity.com/mod/gallery/index.php?image_id=1808082)[http://www.renderosity.com/mod/gallery/index.php?image_id=1837070

](http://www.renderosity.com/mod/gallery/index.php?image_id=1837070)[http://www.renderosity.com/mod/gallery/index.php?image_id=1777015

](http://www.renderosity.com/mod/gallery/index.php?image_id=1777015)[http://www.renderosity.com/mod/gallery/index.php?image_id=1241905

](http://www.renderosity.com/mod/gallery/index.php?image_id=1241905)http://www.renderosity.com/mod/gallery/index.php?image_id=1037758