Zotero [zoh-TAIR-oh] is a free, easy-to-use Firefox extension to help you collect, manage, and cite your research sources. It lives right where you do your work - in the web browser itself.
Because it's based on Netvibes, this resource for Engineering postgrads is bit more dynamic than the library web pages. Don't be put off by the title, most of the resources are applicable to undergraduate research and dissertation projects.