Science fiction fans have a few resources available to find the right book.
LOCUS online is home to one of the big science fiction magazines. New releases, reviews, and talk about the genre can all be found here. Their Index to Science Fiction Awards has a massive list of all the different awards including the Hugo and Nebula awards, and the Locus poll and awards.
The Internet Speculative Fiction Database catalogs works of science fiction, fantasy, and horror. They have recommended reading lists and information about forthcoming books.