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.
Users join a group of 6 and rotate books each month...so you contribute your own book and read 5 others that are sent to you each month. It's pretty cool...and it's free. So far I've read some great books.
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!