The Wire, season 2. It is all centred around the dock in Baltimore: drug traffic, girl traffic, and dockers unions. All of that could be easily converted into an set of adventures: Help rescue girls before they are shipped to slave island. Help drug dealers (or demon magicians) either escape or get supplies in the city -- knowingly or not. Finally, you have docks. Two gangs decide to get in and unionise (sorry, make a guild) and have a racketing ring (sorry, provide a better, saver service).
Film noire. Any of them. All of them. Corrupt officials, McGuffins, femme fatal, dark alleys, and black cats. If your players are up to some detective work, any of those can be easily converted.
Wild west, the reality. Not the Hollywood myth but the real things. Gold rush, ghost towns, cowboys coming and causing trouble, saloons and gambling (whoring), and of course, the law. Look at Doc Holiday and Wyatt Earp at Tombstone for what could be a very very good game indeed. Frontier towns are great, as they allow not only city expansion, greed, but all sorts of "bad things" to come in and out.
Wild West, the fantasy. Pretty much the same as above but now with added myths: seven samurai/magnificent seven, Unforgiven, Once Upon a Time in the West, ten to Yuma... Countless things to be converted.
Beowulf. This is a classical city tale with monster, their Mum turning up to complain, and finally a dragon.
Disc World Anything set in Ankh Morpork (so mostly the guards serie) by Terry Pratchet. Countless source of adventures: What about orcs in the City guards? What about Troll right? How about the characters are the night watch and have to deal with all those pesky, irritating, and stupid adventurers?
Night Watch, Day Watch, Twilight Watch, Last Watch by Sergei Lukyanenko can give you plenty of ideas for a more magical setting. It's modern urban fantasy.
Dresden Files by Jim Butcher should need no introduction.
Kitty Norville by Carrie Vaughn should be a read. Radio talk show, werewolves, and a very real character. Her books are awesome nonetheless.