Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.
MyBib - A new FREE citation generator.
Mendeley - Easily organize your papers, read & annotate your PDFs, collaborate in private or open groups, and securely access your research from everywhere.
EasyBib - Automatic works cited and bibliography formatting for MLA, APA and Chicago/Turabian citation styles.
BibSonomy - BibSonomy is a system for sharing bookmarks and lists of literature (BibTex format).
bibme - Reference management software.