I hype this site pretty often - it's an e-mail book club (actually, a dozen of them, and you can sign up for as many as you want) that makes weekly selections and e-mails you daily excerpts. It's a convenient way to sample books, and I've found a lot I wanted to read further after getting that taste.
The Bookshelf at Mommy Track'd has book reviews as well as a comprehensive list of reading recommendations all of particular interest to working moms. You will find Books About Balance, See Mom Work Books (featuring kids books where the mom character works), Working Mom Fiction for your Non-Existent Free Time, The Anti-Princess Reading List for kids and more.
A free, worldwide membership community with the goal of "making the whole world a library." Register the books you read and pass them along - you can follow their travels through their BCID numbers. Set your books free, and find new ones for free, too!