gThumb
gThumb is an image viewer and browser for the GNOME Desktop. It also includes an importer tool for transferring photos from cameras.
gThumb is available for most Linux distributions, just do a search for gthumb in the package manager. Ubuntu users can just click here to install the gthumb package.
gThumb is released under the terms of the GNU General Public License
1. Getting in Touch
2. Development Resources
2.1. More information about developing or contributing to gthumb
Development: All sorts of development information, from hacking on gThumb itself, to debugging issues.
Extensions: gThumb has a plug-in system for extensions