In doing so, he would pinpoint the fastest route to our brain's pleasure center.

One of the great things about the Internet is that running an Internet test kitchen is very cheap. Software programs -- including the infamous cookies -- enable application developers to analyze user behavior. Using these tools, the company can not only monitor the crowd's behavior and create products that appeal to large groups but also create experiences designed for the individual. Imagine a recipe tailored to each user with the equivalent of just the right amount of sugar, fat, and salt -- a customized potato chip, burrito, healthy snack, or gummy bear. The food industry, of course, has been designing just such recipes for decades.

There's more good news for the Internet entrepreneur. He won't have to waste a lot of time doing brain research before creating his products. Studies on cigarette, drug, and gambling addiction, along with other forms of compulsive behavior, provide the Internet entrepreneur with yet another design handbook.

The release of the neurotransmitter dopamine acts to turn on the pleasure circuits in our brain. Each inhalation of nicotine generates a small and almost instant dopamine release in our brains -- instant gratification. If this instant-gratification technique works well for cigarettes -- and, many argue, for engineered fast food -- why not use it for video games, Facebook, or instant online dating services?

The right swipe on the touch screen in Angry Birds delivers an instant hit. The constant updating on Facebook pages with interesting tidbits from friends generates the warm feelings that come from close engagement with the "in" crowd. MeetMoi.com will link you up with "singles within a few miles from you who can meet you tonight" -- no need to go through eHarmony's tedious process of communicating with someone before a face-to-face meeting.

Of course, there's something always happening on Twitter. Text messaging, instant messaging, a continuous flow of emails and alerts, keep us returning to our mobile devices and computers to stay permanently engaged. What can be better than an alert when your favorite stock rises or your team wins a key game?

Casinos also excel at keeping customers engaged. We know from studies of the brain that surprising events that deliver unpredictable rewards give us shots of dopamine. It is a mild form of the pleasure rush one gets from injecting heroin and snorting cocaine. For a fraction of gamblers, those shots lead to addiction.

So design your shopping service to deliver an unexpected discount. Yesterday's eBay, where people spent hours and days at a time seeking bargains, is today's Groupon, where the rewards are even quicker. Twitter loves to tell subscribers that some "noted" person mentioned them, prompting a race to the site to find out if said luminary has hundreds of thousands of followers -- what a rush. Financial management firms love to make customers go through sophisticated login procedures even when giving non-secret information. It makes users feel like they're members of an exclusive club and keeps them coming back.