Zotero is a freely available, open source program which allows you to easily save, organize, and cite all of your references. You can work online, or on the free desktop version.
Downloading Zotero
Setting up an account
Saving and importing references
Entering references manually
Importing references from EndNote
Inserting citations in a MS Word document
Creating a bibliography
Mendeley is a free reference manager and academic social network that can help you organize your research, collaborate with others online, and discover the latest research. You can work online, or on the free desktop version.