Zotero Numero Uno
"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." On October 31, it made the great leap from Beta to 1.0 (and, it seems, to 1.0.1—that's the version Firefox just loaded for me). Here's what Team Zotero has to say about it: "We are pleased to announce that the 1.0 release of Zotero is now available. Our dedicated developers have refined and streamlined the Zotero experience, and Zotero is now officially out of its beta testing phase. If you were waiting for that seal of approval, you should now download Zotero immediately!"
"Those upgrading to Zotero 1.0 from earlier betas will notice significant improvements in functionality and stability, and our even more ambitious next phase of major development is already underway as our team focuses on Zotero’s upcoming collaborative features."