1800Student
Textbook exchange for students worldwide, plus used children books and musical items.
http://www.1800student.com/

Got a Book
For students to buy and sell books.
http://www.gotabook.com/index1.htm

Mercantiquo
Matches buyers and sellers with old and rare books.
http://www.mercantiquo.it/

More For Nothing
Offering free ride sharing and used textbook exchanging services. Based in Canada.
http://www.morefornothing.com

One and Ten
Secondhand text books classifieds site for university and college students.
http://www.oneandten.com

Student Listings
Buy and sell book service for college students.
http://www.studentlistings.com/

Swap Books
Service for students to buy, sell and swap used books.
http://www.swapbooks.com/

Text Book Trader
Buy, sell, or trade used textbooks. Based in Canada.
http://www.textbooktrader.ca

Text For Sale
Students buy and sell books; also searches bookstores.
http://www.textforsale.com/

XLCampus.Com
Buy and sell used textbooks directly from students.
http://www.xlcampus.com/

Zoo Ad
Students buying and selling service for text-books.
http://www.zooad.com/