Mendeley is a serious options for those looking at a PDF management (and in text citation) system for scientific literature. It is a rather good option to replace the old-timer Endnote.
Well, Mendeley is now part of the Elsevier family, another major player. It is going to be interesting where this will lead Mendeley in the longer term.
Read the link here: Team Mendeley is joining Elsevier. Good things are about to happen! | Mendeley Blog.