Tellico is a KDE application for organizing your collections. It provides default templates. The data is saved in XML format, which makes for easy parsing. It will run on any platform which KDE supports, most commonly Linux.
abRef is an open source bibliography reference manager. The native file format used by JabRef is BibTeX, the standard LaTeX bibliography format. JabRef runs on the Java VM (version 1.4.2 or greater), and should work equally well on Windows, Linux and Mac