These are for me the best 4 performing stock agencies for August 2011:
Dreamstime. At this point I also like to mention DepositPhotos. If I don't take in account the first view month where I received the promotion to get paid for upload, then August 2011 would have been the best month ever for DepositPhotos. DepositPhotos has shown a constant increase of sales for several month.
(This statistic include referral earning at the different agencies)