Providing an on-line computer database in the field of business information and business contacts; Providing an on-line searchable database featuring business information and business contacts; Providing an on-line searchable database featuring used books being offered for sale and buyer/seller contact information; Provision of commercial and business contact information; Provision of databases featuring listings of marketers for use by others in identifying and contacting marketers for promotional purposes; Updating and maintaining business contact information via the Internet