Percentages and absolute numbers
Percentage of active users in the Internet 2.0 is tiny. Fractions go from
* only 1% of Wikipedia's users contribute to making it better
* only 0.1% of users upload their own videos to Youtube
* only 3% of people with weblogs post on a daily basis
* only 1% of Amazon.com customers contribute with reviews
The numbers are tiny. But not uncommon. Typical return rates of marketing campaigns or surveys are around 2-5% (see report by the Direct Marketing Association). In our experiments of viral marketing campaigns we got up to 8% by triggering the action of clients using a prize contest.
So, how do all these business survive? The reason is absolute numbers. Percentages are small, but absolute numbers are huge:
* 70000 active contributors maintain the Wikipedia
* 65000 videos are uploaded daily to Youtube
* 1.6 million of posts are created daily according to Technorati
Even for the dubious business of email spam, absolute numbers matter: tens/hundreds of people usually answer email spam campaigns. Out of hundreds of millions of emails sent, yielding a 0.0001% response rate [pdf]. But this low response rate does not matter, since sending email spam is a freemium business which uses the near-zero marginal cost of online distribution