BZFlag is a 3D, multiplayer, tank battle zone, capture the flag game that pits players against each other in a networked environment. It runs on Windows 95/98/NT/2000, Linux, MacOS 10.x, Irix, Solaris, and others. An OpenGL accelerator is highly recommended, but it is playable with 3D in software.
Bitcoin is a peer-to-peer electronic cash system that is completely decentralized, without the need for a central server or trusted parties. Users hold the crypto keys to their own money and transact directly with each other, with the help of a P2P network to check for double-spending.
EduKator is a KDE-based education program for learning about physics and mathematics in a way that it is fun. The program explains the theory being taught, and provides exercises for practicing the concepts. It includes programs for teaching the basic rules of optics, representing dubblerates graphically, teaching the basics of Archimedes' principles, and teaching about extrema problems (finding the minimum and maximum values of mathematical functions).
Fotoxx navigates an image collection using a thumbnail browser to choose images to view or edit. Edit functions include brightness, contrast, color, gamma, white balance, tone mapping, red eyes, sharpen, blur, noise suppression, smart erase, trim (crop), resize, rotate, add text, bend/warp, many art effects, HDR, HDF, stack, and panorama. Edit functions use movable curves and sliders. Feedback is live using the whole image. RAW files can be edited and saved with deep color. Areas or objects can be selected using freehand draw, follow edge, and tone matching. Selections can be edited in place with adjustable blending. They can also be cut and pasted into other images. Any metadata can be edited, reported, and searched (filenames, tags, dates, geotags, comments, captions, ratings, etc.). Collections (arbitrary subsets) can be defined and viewed. Batch functions are available for rename, resize/export, RAW conversion, and more.