Delicious Library - Delicious Library 3: Catalog your books, movies, music, software, toys, tools, electronics, & video games. Archive your life.
PostgreSQL - PostgreSQL is a powerful, open source object-relational database system.
Tellico - Tellico is a KDE application for organizing your collections.
MySQL - The world's most popular open source database
Readerware Book Database - The easiest, fastest way to catalog your books, nothing else comes close.
SQLite - SQLite Home Page