Sk-etchbook

Here is some research done into viral marketing

http://www.brandchannel.com/features_effect.asp?pf_id=204

Interesting article about viral marketing. It's history and effectiveness.

http://www.brandrepublic.com/News/867867/Campaigns-top-10-virals-2008/

Top 10 virals of 2008

And these are a couple of books I downloaded on the subject.

The New Rules of Viral Marketing

Viral marketing with blogs