In Ray Bradbury`s short story "A Sound of Thunder", a group of people travel millions of years into the past to hunt dinosaurs. One of them accidentally steps on and kills a butterfly, which dramatically alters the future.

This idea was also taken up in a movie called "The Butterfly Effect", starring Aston Kutcher, about a young man who managed to travel to his past and, by altering earlier events, changed outcomes in his future, including some that were unforeseen.

The butterfly effect has its roots in chaos theory, where a small event can have a ripple effect and bring about possible dramatic changess - the fluttering of a butterfly`s wings possibly forestalling a monsoon that would have devestated an island.

Successful internet marketing is the result of many such "trivial" events at work.

But which ones will prove to be significant and how do we sustain, and even build, the momentum which is generated?

One proven technique is known a viral marketing, which adopts a strategy that encourages many people to pass on a marketing message to others. It makes use of multiplication to "explode" the distribution of the message by willing participants.

Hotmail used this method to get established. When the two founders set up their free email system, all the messages that were sent by subscribers had a text message at the bottom whiich identified Hotmail as the origin. People would send emails to their friends, who would be tempted to set up hotmail accounts and send emails to their friends...