My colleagues Clai Rice and Jonathon Goodwin swear by Zotero. I hated it as a Firefox extension, but it is now available as a standalone app. I tried it at 1.0 and it was not ready yet, but at RC 3, it is beginning to get interesting. It even began to sync some data I had synced a very long time ago, which was good, but then it took over my CPU cycles, and that was not so good:
Scholarly Electronic Publishing Bibliography presents selected English-language articles, books, and other printed and electronic sources that are useful in understanding scholarly electronic publishing efforts on the Internet. The bibliography covers a wide range of topics, such as digital copyright, digital libraries, digital preservation, digital repositories, e-books, e-journals, license agreements, metadata, and open access.