The Role Playing Database maintains data files containing information about the players, monsters, spells, treasures, tricks, traps, etc. used in table-top role playing games, such as Dungeons and Dragons. It also provides a way to make maps of the playing environment (e.g. dungeons) in which the game(s) take place.
Scid vs. PC is a powerful chess toolkit. It has extensive database and PGN file handling capabilities, and can be used to play chess on the internet (with FICS), against a computer chess opponent, or for chess grandmasters to prepare for tournament matches. Additionally, Scid vs. PC can run automated computer tournaments with chess engines playing against each other.
Pixane is an image processing library for Tcl that allows the scripting of all kind of image transformations. It supports reading from and writing to a large set of file formats (JPEG, PNG, GIF, BMP, WBMP, etc) and provides anti-aliased text rendering and a set of built-in fonts. It doesn't requires Tk, so it can be used to easily generate images dynamically from CGI. Binaries are provided for many platforms as dynamic libraries with no external dependencies for easy deployment. It is also a core component of the eTcl distribution.