There are a few popular approaches to presenting custom content. One such technique, rules-based filtering, runs user information through software that decides which pages and what content to present. Another approach, collaborative filtering, combines user data with information about what similar visitors have purchased or recommended. A book or music site might make purchase suggestions by telling users something like "People who bought that product also bought this one."
Customization is accomplished with programs that work with your Web server software. Not long ago, personalization programs had to be custom-written and were very costly. Only the largest e-commerce sites could afford them. Now a start-up can buy complete customization packages off-the-shelf. Yet, customization still isn't cheap; most is done by sites with budgets above $500,000, Avedikian says. But it's rapidly becoming more affordable. You can download scripts offering some degree of customization for as little as $1,000. (Check http://www.cgi-resources.com for examples.) Even at those prices, customization isn't for every site, says Bernadette Tiernan, author of the e-commerce manual e-tailing: Profits from the E-Commerce Explosion (Dearborn Financial Publishing, $25, http://www.dearborn.com). "The technology has to support customer needs," Tiernan says.
If you do it, do it right-because you've got a lot of competition. "All those sites that were doing [a little of this] a few years ago," warns Fulop, "are doing a lot more today."