Photo buffs who are fond of open source software would do well to look at blueMarine. Right now, the free, cross-platform application's strength is image management, but it is on its way to becoming a complete workflow tool. Its cataloging features are robust, its architecture is extensible, and it takes some intriguing new approaches.
Java consultant Fabrizio Giudici started the project in 2003, but it languished as he grew frustrated with the limitations of the Swing toolkit. In 2006, he rebuilt the code using the newly released NetBeans platform, and hasn't looked back since.
You can download binary blueMarine packages from the project's Web site for Linux, Windows, and Mac OS X. The Linux version is available as a JAR package and as a .deb file. In addition to the latest stable release, you can grab development snapshots from the project's java.net development site. They are designated as not-for-production use, but allow you to explore some of the app's newer features. All require an up-to-date Java environment for your OS.