Excellent intro to viral marketing. Thanks for that.

I just wanted to add one small thing, which has been preached over and over again in Internet marketing, and also applies by nature to viral marketing.

I have seen people try to do viral marketing with many products, but most e-business fail because they don't give the customers what they want, but what they think they want.

In viral marketing for any product, it is essential that the viral component is like a "virus" that is the definition of viral marketing, and if the "thing" given away to spread and create more customers or whatever is not something that is of "wide" and I mean "very wide" interest to spread and extremely "addictive" to spread a viral marketing will stop short very fast. (e.g. I can't stop myself for not sending this to another person because: 1. it is extremely good/useful/entertaining 2. the incentives are extremely irresistable. The second option is usually when less qualified leads and customers come to the originator of the marketing campaign).

I found that viral marketing is not easy, by far, and extensive customer research usually goes into it, or pure luck for some (for ICQ it was pure luck of the draw, the right product at the right time give out for free).