calibre - Ebook manager, viewer & converter
Delicious Library - Delicious Library 3: Catalog your books, movies, music, software, toys, tools, electronics, & video games. Archive your life.
tinyMediaManager - A multi OS media manager written in Java/Swing
Tellico - Tellico is a KDE application for organizing your collections.
Readerware Book Database - The easiest, fastest way to catalog your books, nothing else comes close.
Data Crow - Data Crow is the ultimate media cataloger and media organiser.