GIMP is the GNU Image Manipulation Program. It is a freely distributed piece of software suitable for such tasks as photo retouching, image composition and image authoring. It can be used as a simple paint program, an expert quality photo retouching program, an online batch processing system, a mass production image renderer, a image format converter, etc.
Image Viewer is a multi-frame (animated) image viewer with real-time interactive pan and zoom viewing that uses the GTK+ toolkit and Imlib. It is capable of opening and saving to any image format supported by Imlib. It features screenshots (screen capture), crop, resizing, print, fullscreen display, display on the desktop (root window), animation (creating animated GIFs), color leveling, drawing font/text strings, and editing image header information.
Songwrite is a tablature editor. It supports many string instruments in addition to traditional staff notation. You can edit tablature (guitar, bass, banjo, etc.) and staff notation, add lyrics, create your own songbook, play your partitions, print your partitions and your songs, automatically convert staff notation to tablature and vice-versa, export songs to many formats (PDF, MIDI, ASCII tablature, GNU Lilypond, LaTeX, PostScript, etc.), and import Guitar Pro 3/4 files (experimental).
"Jpegpixi" is short for "JPEG pixel interpolator". It is a command-line utility which interpolates pixels in JFIF images (commonly refered to as "JPEG images"). This is useful to correct images from a digital camera with CCD defects. Jpegpixi is unique in that it tries to preserve the quality of the JFIF image as much as possible. Most graphics programs decode JFIF images when they are loaded, and re-encode them when they are saved, which results in an overall loss of quality. Jpegpixi, on the other hand, does not decode and re-encode the image, but manipulates the encoded image data, protecting the quality of the image as much as possible.
Tux Paint is a simple and entertaining drawing program geared towards young children. It has a simple interface, sound effects, and a cartoon character (Tux, the Linux penguin). Along with drawing brush strokes, lines and shapes, you can also enter text and place "rubber stamp" (or "sticker") images on the picture. Tux Paint is extensible, and could be useful in an educational environment (such as a grammar, elementary, or grade school). It's portable across numerous platforms, and runs well even on slower systems like the Pentium 133MHz.
digiKam is an advanced digital photo management application that makes importing and organizing digital photos a trivial task. Photos can be organized in albums, which can be sorted chronologically, by directory layout, or by custom collections, and they can be tagged, commented, and rated. digiKam makes use of a fast and robust database to store meta-information, which makes adding and editing comments and tags very reliable. Metadata can also be stored inside pictures using Exif and IPTC. An embedded image editor and a standalone application named showfoto have simple but powerful features for editing your pictures with filters and correction tools.