"Academic social media" sites are targeted toward researchers and academics, but the same cautions exist here as on Twitter, Facebook, and other more social sites. Be aware of your audience, privacy settings, and your digital reach.
ResearchGate "Our mission is to connect researchers and make it easy for them to share and access scientific output, knowledge, and expertise."
Academia.edu "A platform for academics to share research papers. The company's mission is to accelerate the world's research."
Figshare "a repository where users can make all of their research outputs available in a citable, shareable and discoverable manner"
Mendeley "a free reference manager and academic social network"
LinkedIn "To connect the world's professionals to make them more productive and successful."
SlideShare "Show what you know through a presentation, infographic, document or videos" (part of LinkedIn)
SpeakerDeck Share presentation slides online (part of GitHub)
Graphic from Nature 512, 126–129 (14 August 2014), doi:10.1038/512126a