Well, if you're looking for something more structured, you might want to check out Urban Fantasy Hero from Hero Games. You can't get much more structured than the Hero System.
I haven't actually played UFH myself, but i run Champions which uses Hero System, and I've incorporated various urban fantasy elements for the mystical side of my campaign world. Vampire anarchs, feral werewolves, worm tainted corps, and cruel fey tricksters are just some of the varied urban fantasy encounters the player superheroes have encountered in the past.
Hero system is i think one of the best balanced systems for structure and creativity, allowing you to make what you want while giving you the structure to keep things from breaking down into debates about what ones character can or can't do in the rules.