It is a great idea. It is not very fast/successful in the sense of what most people would consider successful.. such as having a bunch of spam sites that could trick users into generating cash for them. I think this tool is being abused like a mother fucker but could be beneficial in the ways theoretically thought about initially, but kinks need to be worked out and people need to code, unfortunately the payoff on such a project would probably not be the pay day that one would expect from such a technology. Thus, no one seems to be pushing this.
Also, you should look to this thread where someone seems to have the same line as thought as you and beat you to asking about this
http://forum.bitcoin.org/index.php?topic=21185.0
