Library 2.0 Ning is my favorite social network because it promotes serendipitous searching among people who have the same profession as well as an interest in web 2.0 in common.
If you are a fan of serendipitous searching, check out Steve Nelson's BananaSlug, which was designed to promote serendipitous surfing.
"Directed Google searches return pages most relevant to your search term, based…