Operating on-line marketplaces featuring books; Operating on-line marketplaces for sellers and buyers of goods and/or services; Providing a website featuring on-line classified advertisements in the field of books; Providing a website featuring on-line classified advertisements; On-line retail store services featuring a wide variety of consumer goods of others; Providing a buy-back and trade-in program for used textbooks of others; Providing a website featuring an online marketplace for excha...