1% rule

An early concept that suggests that if you get a group of 100 people online, then one will create content, ten will interact with it (commenting or offering improvements) and the other 89 will just view it (also known as lurking).

Early metrics garnered from online community sites suggested that about 80% of content was produced by 20% of the users, but the growing data due to social networking sites and blogs creates a different picture. The lesson? A Web site that demands too much interaction and content generation from users will see nine out of ten people just pass by.

See also : the long tail  Web 2.0  
NetLingo Classification: Online Marketing