What is the best PPC program for social bookmarking websites?

I have a few social bookmarking websites and I’m currently using AdSense. I have used AdBrite for a short while, but the earnings are very low compared to Adsense.
Does anyone has used any other PPC program on a social bookmarking website? Can you share your experience with us? Which PPC program can bring better results than Adsense?
thank you

See original post by q7m