I've been on DP for a month now (thanks to Fotolia drawing attention to it) and my earnings there are about 5% of my earnings over the same period from iStock (excluding PP) and about 3% of SS. In cash terms, it's not much, but its really impressive for a site that only started up in the last couple of years and which I think has quite limited name-recognition so far. The sales frequency I'm getting seems to be much the same as I was getting on SS back in 2005 when it was a similar age.