Just a heads up that for the next 30 days you can read Neil Gaiman's Neverwhere for free by going to this link through his journal. I've had this on my list of books to read for a while now, so I'm definitely going to download this and do some major reading for the next 30 days.
And now, a quick synopsis from Amazon.com:
Neverwhere's protagonist, Richard Mayhew, learns the hard way that no good deed goes unpunished. He ceases to exist in the ordinary world of London Above, and joins a quest through the dark and dangerous London Below, a shadow city of lost and forgotten people, places, and times. His companions are Door, who is trying to find out who hired the assassins who murdered her family and why; the Marquis of Carabas, a trickster who trades services for very big favors; and Hunter, a mysterious lady who guards bodies and hunts only the biggest game. London Below is a wonderfully realized shadow world, and the story plunges through it like an express passing local stations, with plenty of action and a satisfying conclusion.