Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share your research sources.
Mendeley is a free reference manager and academic social network.
EndNote is available from the university's LAN.
CiteULike is based on the principle of social bookmarking and is aimed to promote and to develop the sharing of scientific references amongst researchers.
ReadCube is an excellent tool for organizing, finding, reading and annotating PDF articles.