"For adoption of new technologies in science, it has to be an order of magnitude more useful than current tools. We just don’t have the time to waste learning new tools that only marginally increase our productivity." Discussion: http://friendfeed.com/science-2-0/bceaea67/scientists-still-not-joining-social-networks
EndnoteWeb, RefWorks, Connotea, CiteULike, Zotero, Mendeley. Nice summary of the state of the art by Martin Fenner. Conclusion - not much to choose in some ways - personal preference!
A free editing service for developing country researchers who are trying to publish their work has been launched by students from leading academic institutions. The service, SciEdit, is run by a team of undergraduate and postgraduate students in Canada, Europe and the United States. They aim to provide detailed editorial feedback in accordance with the standards of journals such as Nature and Science - where many of them have been published.
"free, social networking site that enables scientists, engineers, and other technical professionals to connect, collaborate with ... world-wide scientific communication and incorporates the newest social networking technologies." - "Yet another Facebook for Scientists that I am unlikely to use." http://tinyurl.com/55ngbf