I've been describing my superhero novel--well, it's more of a deconstruction of superhero stories--as urban fantasy because there was originally no scientific explanation for the sudden development of increased psychic ability (read: superpowers) in humans. But in the most recent draft, scientists are studying increased psychic ability and are making progress (for instance, one researcher figures out what predisposes people to increased psychic ability), so that rings more sci-fi to me. The story is also about an anti-hero who uncovers a conspiracy to kill hundreds of people and blame it on exposure to psychic power, so there's a race-against-time element as the main character tries to take down the conspiracy. Would that make it a thriller? I've never had so much trouble putting a genre label on a story before, and I can't very well go looking for an agent if I don't know what genre my own damn story is.