RefWorks is a tool for organizing and sharing your research materials and citing them in a wide range of citation styles.
Zotero is an easy to use application for organizing your research materials, sharing them with collaborators, and citing them in a wide range of citation styles. It's free. Works best with Firefox.
Refworks: Annotate pdfs, cloud based.
Zotero: cloud and web based
Both: organize sources, sharing folders, importing citations from databases, capturing citations from websites, create citations.
Contact your librarians for help with citations: Aaron Albertson (albertson @macalester.edu) & Beth Hillemann (hillemann @macalester.edu).
The Writing Center at Purdue University has created the most widely used, comprehensive guides to citation available.