One of the theories that often goes around forums that discuss the use of Adsense is that site that use it get indexed faster and higher than sites that don?t. The theory goes that if you use Adsense - Google will want your site to be more successful (and therefore earn them extra money) and so it will do its best to get your site seen by as many people as possible by giving it a high page ranking. Google denies this to be the case in their promotion of Adsense.

I?ve often thought that it would be interesting to test this theory - but never got around to it. Luckily someone else has.