Morton Grove Public Library Booklists – Incredible array of booklists sorted any way you can imagine
http://www.webrary.org/rs/flbklistmenu.html

What’s Next? Books in Series from the Kent District Library site
http://ww2.kdl.org/libcat/WhatsNextNEW.asp

AllReaders.com – Great way to search by title, author, character, plot, or setting
http://www.allreaders.com/default.asp

The New York Times Current Bestsellers
http://www.nytimes.com/pages/books/bestseller/

FictionDB – offers complete book lists, book details and synopsis, and series lists for free
http://www.fictiondb.com/

Overbooked: A Resource for Readers – annotated lists of nonfiction, fiction and mystery books which received starred reviews, themed booklists, featured titles lists and hot lists of hard cover US fiction releases and notable books  http://www.overbooked.org/