There are many academic and professional networking sites which provide a platform to:
Academia.edu is a for-profit company. It is an academic networking site that allows you to:
For examples see Monash University on Academia.edu
ResearchGate is a for-profit company. It provides a free social network for scientists in which you can:
SSRN is a global collaborative composed of a number of research networks, which aims to make social science research rapidly available and to facilitate direct communication amongst authors and readers. SSRN is owned by Elsevier.
The SSRN eLibrary consists of two parts: an Abstract Database where you can upload your abstracts, and an Electronic Paper Collection where you can upload your full papers. Registered users can download these for free.
Humanities Commons Network is a project of the office of scholarly communication at the Modern Language Association.
It's development was funded by a grant from the Andrew W. Mellon Foundation.
Mendeley is a reference manager and an academic social network owned by Elsevier.
LinkedIn is a global, career and industry oriented, social networking service for all professionals. See also the related LinkedIn for Higher Ed Professionals. LinkedIn is owned by Microsoft.
Employers can post jobs and job seekers can post their CVs. LinkedIn profiles may be ranked highly in search engine results.
LinkedIn users include businesses and individuals who can create profiles and connections to others who may represent their real-world professional relationships.
Users can invite anyone to make a connection. It is recommended that users only accept connection requests from people that they know, or from those for which the connection may be mutually beneficial.