Yesterday, a friend of mine Dmitry Konstantinov told me about Mendeley. His problem was he had got a lot of papers within his computer and needed to handle them efficiently. After digging the Internet, he found Mendeley reference management system. The system allows you to sort papers, extract the title, abstract, authors, and references from textual PDFs, automatically retrieve meta-information about them from services like CiteSeerx, annotate papers and even their paragraphs, tag papers, flag them as read/favourite etc. Full text search across all your library is very convenient too.