Mendeley - Easily organize your papers, read & annotate your PDFs, collaborate in private or open groups, and securely access your research from everywhere.
Bookmark OS - Bookmark OS is like Mac or Windows optimized for bookmarks.
Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.
Bookmarked - Create, share, and browse curated bookmark collections.
Qiqqa - Qiqqa is a free research and reference management software. It can be used in many organizational projects from the academic to the personal to the business endeavor. Read more about Qiqqa.
Salt - Fast, scalable and flexible software for data center automation