http://arxiv.org/ is a social networking site that is hosted by Cornell University Library. It is used to share working papers and to actually publish academic papers. It is widely used in the quantitative sciences and is beginning to displace actual journals.
The authors springboard from a Cornell University study of the difficulties that humanities doctoral students have in finishing their degree to discuss the ways libraries can help improve student success. They show that the establishment of communities of practice are a necessary component of the success of doctoral students in the humanities. They then advocate for libraries to create and support these communities through providing designated space for doctoral students to collaborate and share information in the library and by offering discipline-specific research skills workshops.