3Delight is a very fast RenderMan-compliant renderer designed to produce photorealistic images for serious production environments. Some of its features include ray tracing, global illumination, motion blur, depth of field, subdivision surfaces, programmable shaders, quality antialiasing, and antialiased multi-depth shadow maps. The API and the shading language are very similar to what is described in the RenderMan interface documentation.
album is a free HTML/XHTML photo album and gallery generator that supports themes/skins. You can choose different themes or write your own to get different layouts and styles. It creates all your thumbnails (including directory thumbnails) and descends into directories so you can organize your photos. See the home page for more examples. album is also multi-lingual, with many languages being added all the time. N.B.: The purchase link is provided for donations; the software does not cost anything.
Allegro is a multi-platform game library for C/C++ developers that provides many functions for graphics, sounds, player input (keyboard, mouse, and joystick), and timers. It also provides fixed and floating point mathematical functions, 3D functions, file management functions, compressed datafile, and a GUI.
amber aims to be an easy-to-use granular synthesis tool for Linux to assist composers and electronic musicians in creating interesting and complex sounds. More information on the theory and application of granular synthesis techniques can be found at http://shoko.calarts.edu/~eric/gs.html.