Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
If you're finding DigiKam or F-Spot, two of the many photo organization and editing tools for Linux, a bit limiting you may want to give Lightzone a try. The software isn't free, and curiously, isn't available for purchase either, but judging by the 20-day demo version currently available, it could end up a serious contender in the hybrid photo editing/managing market.
Linux used to be a second class citizen when it came digital photography, but that has changed in the last couple of years with high quality photo editing and management tools now available. However, digital photography is rapidly evolving and workflows change, for many the preferred way to shoot images these days is RAW and the preferred management/editing package is something like Photoshop Lightroom or Apple Aperture.