Although more than a few e-commerce sites have invested heavily in graphic design, fewer have used the truly killer application of the medium: interactivity. Having a pretty Web site is one thing. Designing an interactive Web environment that will make it simple for customers to do business with you over the Internet is quite another.

According to Stella Gassaway, co-author of Designing Multimedia Web Sites (Hayden Books), "Multimedia applications have transformed the Web from a publishing medium to an interactive medium. The word 'interactive' has come to represent the most dramatic demonstrations of user control."

Fortunately, one of the inspiring things about the Web is that innovative twists offering slicker and slicker e-commerce interactivity are emerging all the time. For example, take the e-commerce site for 49-year-old Judy McCutchin's company, Dallas-based Dallas Real Estate . Visitors here can use a search enging to find products-in McCutchin's case, homes-in the price bracket they can afford. Moreover, each listing is accompanied by a picture of the property, a map and a telephone number visitors can call for more details. No muss, no fuss.

Or take Lombard, Illinois-based Promo-Stats Inc. , a supplier of promotional product giveaways. Well aware that the age of the high-speed Internet on a mass scale is years off, Promo-Stats offers a text-driven product search tool. According to founder and president Frank Typpi, 45, it enables potential customers to quickly search the Promo-Stats product database with Handy text descriptions and/or easy-on-the-download product sketches. Quite insightfully, Promo-Stats realizes that customers dialing in on 28.8Kbps and 56Kbps modems would rather spend their precious time evaluating and ordering products than sitting and waiting for an unending procession of pretty but bloated product graphics to freeze up their PC screens and leave them hanging.

E-commerce site interactivity can also mean providing a plethora of interactive tools that enable potential customers to learn more about products, either from an online program or an online expert. Janet H. Ridder , a realtor in Grosse Pointe Farms, Michigan, for example, makes the most of this approach by devoting an entire domain of her site to free advice related to all facets of homebuying and relocation. Some of Ridder's links point to online calculators customers can use to figure out mortgage interest rates and calculate salary differentials by state. And other links lead to bulletin boards and e-mail response services, where human experts answer questions on moving, home architecture and the like. Ultimately, every e-commerce site worth its salt will create its own spin on interactivity to get the most from the technology. But as with most things Internet, there will always be certain sites that will push the technology just a bit further and be just a tad more innovative than the rest.

A few firms are also starting to experiment with streaming video as an interactive tool. Although it's still an extremely nascent technology among entrepreneurs, streaming video can be used to conduct face-to-face interactions, product demos and the like with customers or business associates who have PC-compatible cameras hooked up to their computers.

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J.W. Dysart , a software analyst and Internet business consultant, has written for more than 40 publications, including The New York Times.