https://www.zotero.org/
A personal research assistant.
Zotero is the only research tool that automatically senses content in your web browser, allowing you to add it to your personal library with a single click. Whether you're searching for a preprint on arXiv.org, a journal article from JSTOR, a news story from the New York Times, or a book from your university library catalog, Zotero has you covered with support for thousands of sites.
Make sure to vote for it in our poll :)
https://patchmypc.net/vote-for-new-apps