Version 2 of Zotero, the free, open-source, cross-platform reference management software, is now available. From the Zotero Web site:
Zotero [zoh-TAIR-oh] is a free, easy-to-use Firefox extension to help you collect, manage, cite, and share your research sources. It lives right where you do your work—in the web browser itself.
Zotero is an excellent all-round research tool, and the cost ($0.00) is hard to beat. Because it runs inside of the Firefox Web browser, Zotero can instantly capture reference data from Web sites and other sources, collecting citation information on books, journal articles, and other sources with a single click. Entire Web pages can be archived in your personal reference library, which can also store related PDFs (Portable Document Format) and other file types, images, and links.
Zotero creates a database on your local computer but can also synchronize your data with its server, for free, making it possible to access your references from any Internet-connected computer. In addition, Zotero users are allocated 100mb of free network storage for supplementary files (e.g. full-text PDFs of journal articles), and you can also upgrade your Zotero network file storage “for a very reasonable cost” (see Planet Earth Likes Zotero File Storage). Another useful feature is the ability of Zotero to scan PDF files, extract the citation metadata, and automatically add the reference to your database (as long as the reference can be found in Google Scholar).
An excellent introduction to the practical aspects of using Zotero can be found in the article “How to Clip, Sort, and Cite the Entire Web with Zotero.”