Zotero was developed by George Mason's Center for History and New Media, which has developed several other interesting programs as well. Zotero is an extension to firefox and you can read more about it and download the extension here. The NY Times recently reviewed it, along with the Mac only Papers. The review was positive, but the author preferred Papers for organizing downloaded papers. Interested readers might also like this post by Rachel Leow, author of the blog A Historian's Craft, about DevonThink, another Mac only program. Does anyone have any other programs they would recommend?
I use a pc for most of my work so now I am relying on Zotero, but am open to alternatives. One lesson I've learned is that it's best to pick one platform, stick with it, and spend your time writing rather than worrying about managing academic citations. Push comes to shove, I can throw together a bibliography for an article much faster than the article itself, so I spend my time accordingly.
Here's the product info for Zotero:
Zotero is a free, easy-to-use, open source research tool that runs in the Firefox web browser and helps scholars gather and organize, annotate, organize, and share the results of their research. It includes the best parts of older reference manager software (like EndNote)—the ability to store full reference information in author, title, and publication fields and to export that as formatted references—and the best parts of modern software such as del.icio.us or iTunes, like the ability to sort, tag, and search in advanced ways. Using its unique ability to sense when you are viewing a book, article, or other resource on the web, Zotero will—on many major research sites—find and automatically save the full reference information for you in the correct fields. Visit CHNM's Zotero site for further information.