My favorite sources of book reviews are:
- The New York Times Book Review (http://www.nybooks.com/)
- The Times Literary Supplement (http://www.the-tls.co.uk/tls/).
- The Economist's book section
I also find Amazon's suggestions, based on my previous purchases and wish list, are pretty pertinent.
Of course there's nothing like old-fashioned browsing in bookstores. Too bad there are fewer and fewer of them.