Mendeley is a dynamic citation management system for collecting and organizing sources that allows users to easily cite them in documents and format bibliographies.
You can drag and drop PDFs into your Mendelay library, and it extracts the citation data for you. Voila, you have references!
You can highlight and annotate PDFs and share them with others. Colleagues can then annotate the same document, with each author displaying as a different color.
Use more than one computer? No problem! Download Mendeley Desktop to multiple computers and then sync your resource lists with a click of your mouse. Need access to your resources away from your computer? Use Mendeley Web!
Mendeley is social: create a profile, follow other researchers, create a network of people doing similar research. Discover the articles being read in your field now.
Create collections of papers. Make them public and share them with an RSS feed (great for class reading lists!).
Mendeley's free version has some limitations on space (1 GB web storage, 500 MB each for personal shared storage) and users (5) and shared collections (10), but you can purchase premium plans for more web and personal storage space and more users and shared groups.
Mendeley serves as a heavy-duty citation manager, suitable for long-term research projects.
It is also a great tool for organizing a robust collection of PDFs.
Mendeley also provides users with a rich social networking experience (similar to that of Last.fm) by allowing you to make your work discoverable to other researchers.