What are some alternatives?
Mendeley - Easily organize your papers, read & annotate your PDFs, collaborate in private or open groups, and securely access your research from everywhere.
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.
JabRef - Graphical Java application for managing bibtex (. bib) databases.JabRef · JabRef Help · JabRef | Blog · OpenOffice/LibreOffice .
EndNote - EndNote is the industry standard when it comes to reference management in a comprehensive format.
FreeMind - FreeMind is a premier free mind-mapping software written in Java.
XMind - XMind is a brainstorming and mind mapping application.