Academia.edu: Social Network in Science
It displays academics around the world in a tree format, according to what university/department they are affiliated with.
It enables an academic to have an easy-to-maintain academic webpage. A sample page on Academia.edu is here: RichardPrice
Researchers don’t have enough time to construct web pages for themselves (where to host it, how to design it) so Academia.edu helps them how to do that. Good idea, great implementation.