ResearchGate

ResearchGate is a hub for a researcher's work, publications, contributions, skills, and interests. Started back in 2008, it now has over 3 million members. Scientists use the site to find collaborators for research, who may be hard to otherwise find, particularly in certain specific areas. Its goal is to help make scientific research more transparent. It has gotten the most traction in biology, medicine, computer science, physics and chemistry.