SciLink
SciLink is like MySpace, but it's for scientists. SciLink provides a networking environment with management tools. Using data mining techniques, it claims to have established a database of over 5,800,000 scientists with over 104 million relationships, and SciLInk knows who is connected to who. It has an article database, a tree of science, a job board, and a science news section; all are searchable. SciLink is free, but registration is required to get its full benefits.