LifeLines is a genealogy program to help with your family history research. Its primarily strengths are its powerful scripting language and the ability easily import and export information in the GEDCOM format.
Clio is a MUD client specifically for MUD2 (a direct descendant of Trubshaw & Bartle's original MUD), but which can also be used with any MUD. Features include ANSI colour, colour logging, scroll back, function keys, command editing, and command history.
A cross platform emacs like editor and assorted tools.
A text-mode (curses) multiplayer game like Konquest (a turn based strategy; you send ships from planet to planet to conquer them). Has better interface usability (e.g. it already has an auto-send feature and save/load functionality). Made in Israel.