It, by Stephen King.
Plot: In 1958, seven children are pulled together through either fate or circumstance, and fight the unspeakable evil that lurks in their town, an evil which takes children, including one of their brothers. Twenty-seven years later they are called back to the town to face the evil once again...
This was a ...chunky book to say the least (my paperback copy was over 1100 pages long). I did find at some points that the plot got a little bogged down in the detail (it worked sometimes for suspense, but not always). As the climax approached however, the plot swapped between past an present in a way that really moved the story along. From the King books I have read I would say this is pretty typical (although I haven't read any of his newer books), by that I mean it's psychological, with the occasional burst of gore. The idea of It preying on fears, and being tuned into those fears is a good one, and the notion of people choosing not to see what is happening under their noses is sadly something that happens in real life. I won't be reading the book again any time soon, but that's not saying it's bad. It was well written and did grip me. For those who have seen the TV movie they made in the 90's, I would suggest reading the book if you haven't already, as the ending of the movie is rushed. The book is better in that respect.
Can anyone explain the "floating" thing- is it to do with the dead? Also, why Bob Gray? It seems strange that It personified itself in such a way, I can understand the clown, which is both friendly and scary at the same time, but not why he chose that name.