gPhoto is a program and library framework that lets users download pictures from their digital cameras. The libgphoto2 library gives you access to hundreds of models of digital cameras on several platforms. GIT repo and Issue tracker lives at https://github.com/gphoto/ these days.
Comix is a user-friendly, customizable image viewer. It is specifically designed to handle comic books, but also serves as a generic viewer. It reads images in ZIP, RAR or tar archives (also gzip or bzip2 compressed) as well as plain image files.
LinPHA is an easy to use, multilingual, flexible photo/image archive/album/gallery written in PHP. It uses a SQL database to store information about your pictures. It comes with a HTML based installer, so you don't need experience in setting up SQL
The program MinDia can be used to create, modify and run multimedia slide shows with a diaprojector Rolleivision 35 Twin digital P (with RS232 interface).
Open source Linux app for photo editing and collection management
Navigate a large image collection using a thumbnail browser, click on an image to view or edit. A rich set of edit and retouch functions is available. Import RAW files and edit with deep color. Save revised images as JPEG, PNG (8/16 bits), or TIFF (8/16). Select an object or area within an image (freehand outline, follow edges, select matching tones, ... ), apply edit functions, copy and paste, resize, blend, warp, etc. without using layers. Edit functions have fast feedback using the full image. Add metadata to images (tags, geotags, dates, ratings, captions ...). Search images using any metadata and/or folder and file names or partial names. Batch functions are available for renaming, adding metadata, moving, converting, resizing, and RAW conversion. Fotoxx uses your image files wherever they are and maintains a separate index for fast searching. Fotoxx is standards compliant and can be used with other photo edit programs (no lock-in).
PhotoSun is a photo manager that aims at easy use. It aims to have to same high functionality as commercial alternatives.