How Much Do You Know About / Use Yahoo!'s Site Explorer and Link Datahttp://www.seomoz.org/blog/how-much-do-you...d-link-researchQUOTE
Yahoo!, through both Site Explorer and their advanced link search operators, provides the most robust link data currently available on the web. Despite this offering, and in spite of some excellent blog posts and resources on this subject (1, 2, 3), it seems that not everyone doing SEO professionally is familiar with how to use Yahoo!'s data to the fullest extent. Even worse, we might not all be aware of how critical it is to measure, quantify and review links. This post is going to take a stab at solving some of these issues and determining if there's more that needs to be done.