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.
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.
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.