Zotero - a free bibliographic manager available as a software plugin in your web browser. Zotero collects, manages, and cites research from multiple types of sources. Through Zotero you can organize your research into different folders for different projects. Zotero can create bibliographies using Word or OpenOffice. Zotero provides a series of tutorial videos to get you started.
Mendeley - a free reference manager that allows you to manage citations and PDFs. It includes plugins for Word and OpenOffice to create citations and/or bibliographies as you write. Unlike other similar tools, Mendeley is a social networking tool that allows you to connect and share with other researchers and students - you can even login via Facebook.