Sciencedaily.com is a very nice and informative site and ranks in the top 6000 sites according to Alexa. They must make a killing from Adsense. However, one thing that I have noticed is that a good 70% of their articles are reprints (exactly same as the original articles). They are mostly taken from university studies and research papers and basically posted adsense codes on their pages. I must stress they do mention where the articles originate and have links to them. Are they allowed to do this? Aren't they making money from other's writing.
Perhaps, they have an agreement to share adsense and other revenues generated, though I doubt this very much.