Yahoo finance (last year) had 20 million unique readers. That probably gives you an idea of the scale of how many people are individual investors or interested in investing.
We're looking for investors, rather than traders. We're more focused on the long-term horizon.
The only issue I have with Yahoo Finance figure is that the greater majority of those uniques will be there for news on the financial markets, which is a service we will not provide, at least in the near term.
http://gigaom.com/2009/07/16/yahoos-number-ones-so-much-more...