A site designed to sell a product is far different than a true reference site with hundreds and hundreds of pages of free information on a particular subject. The best analogy I can think of to explain a sales-focused web site is a public library. A library is, first and foremost, about content, although it does sell things. You can buy copies of books, order maps, buy online database search time, or rent study offices or PCs. Some libraries even have video-rental services and snack shops or restaurants.
Money definitely changes hands at a library.
In a like manner, a web site also needs to be a library of information on whatever its focus might be. Add great content to your product site. Because useful content gets linked. In 1994, Eric Ward founded the web's first service for announcing web sites to online editors, writers, and site reviewers, and he still offers those services today. His services won the 1995 Tenagra Award for Internet Marketing Excellence, and Websight Magazine selected him as one of the web s 100 most influential people.