Bookbyte.com
Buy or sell any book; school books, text books, reference books.
http://www.bookbyte.com/

eHarlequin.com
Romance books online.
http://www.eharlequin.com/

Chegg.com
Textbook rental service.
http://www.chegg.com/

College textbook rental
College textbooks
http://www.collegebookrenter.com/

CampusBookRentals.com
Rents textbooks to college students across the nation.
http://www.campusbookrentals.com/

Booksonline
Direct marketer of 20 different general interest and specialty book clubs.
http://www.booksonline.com/