Xtank is a fairly old but reliable graphical game requiring multiple players and optimised for a local area network of X displays. It features fast update rates, assorted mazes, various vehicles, simple graphics, drone tanks, and team play. Different game styles are possible; straight combat, territorial expansion, maze races with and without weapons, and ultimate frisbee. The "north" development branch is James Cameron's modifications to the 1.3f version for use on 800x600 displays in a network of Linux based second-hand gaming workstations in a rural village.
PilotGOne is a GO game viewer and recorder for PalmOS. It uses the Smart Game Format (SGF) for input and output. PilotGOne can play back existing SGF files with variations and comments, and it can also be used as a board for stand-alone play. It uses only 42 Kb of Palm Pilot memory, and it supports comments, marks/labels, and annotations. Other features include Zoom-In for bigger image, editing of game records, sorting/searching of games, handicaps, Komi, and board sizes 5x5, 9x9, 13x13, and 19x19.
s3d is an XML schema for 3d scenes, objects, and so forth (intended primarily but not exclusively for computer games). The problem is that often as a games developer you need to work with many 3d editing tools and rendering engines, and there should be an easy and portable way to move objects, levels, etc. around. By having a common intermediate file format, you only need to write one exporter per tool and one importer per graphics engine. Also, you can develop generic tools which are not tied to any particular engine.
rndgen is a Java application that mirrors the functionality available from Leon's Random Generators. They use a database of words and sentence forms to create various kinds of random text, including band names, song lyrics, jokes, advice, and essays. They are whimsical and mostly nonsense. You definitely need a particular sense of humor to appreciate them.