AbeBooks - AbeBooks has millions of new & used books, rare books and out of print books.
Universal Book Reader - Just like its name, Universal Book Reader is really a universal book reading application allowing you to read the eBooks from the convenience of your smartphones.
DealOz.com - Save time. Save money. Discover. Search new and used books, textbooks, and ebooks using the most trusted shopping comparison site, DealOz.com.
Cool Reader - Fast and small cross-platform eBook reader for desktops and handheld devices
Occupy the Bookstore - Chrome extension to easily surface cheaper textbooks
iReader - iReader is one of the most accomplished ways to read the books right from your smartphones.