My buddy Dave just put up a post on his blog about a Conan game he ran when he was in grad school. It was using the Mongoose d20 Conan game, but he's got some good pointers on things he did for that campaign that would be good advice for anyone running a city-based campaign, or any sandbox game where the DM wants to get a noir feel to the game.
It's a good read, and he's got some good advice.
Ratpack – Shattered Star Book 2, Session 33
20 minutes ago