the perfect link profile post pand / penguin:
http://www.libako.de/linkaufbau-studie-9-linkarten
very interesting read, posted on another forum; I personall belive that these guys definitely know what they are talking about, although this is for mainstream sites ... and even if you use Google translator, you should be able to read it ... you can just scroll to the bottom of the article for the perfect link profile pie chart