Delicious Library - Delicious Library 3: Catalog your books, movies, music, software, toys, tools, electronics, & video games. Archive your life.
My Visual Database - Using My Visual Database, you can create databases for invoicing, inventory, CRM, or any specific purpose.
Tellico - Tellico is a KDE application for organizing your collections.
LibreOffice - Base - Base, database, database frontend, LibreOffice, ODF, Open Standards, SQL, ODBC
Readerware Book Database - The easiest, fastest way to catalog your books, nothing else comes close.
Kexi - Kexi | Calligra Suite