nethack-el is an Emacs major mode for playing nethack. Separate buffers are used for the map, status, messages, and menus. It features customization of keys and colors and user programmable hooks on game events. It supports GNU Emacs 20/21 and XEmacs 21, with graphical tiles on *Emacs 21.
Argh! is an esoteric programming language in the spirit of Befunge, Brainfuck, and friends. It is a nice and simple language with two dimensional code-flow, a combined code/data array, an infinite stack, regular characters for all instructions, no strange braces or symbols, no unnecessary arithmetic operators (add and sub are all you need), and countless other features it doesn't have. The distribution includes interpreters for Argh! and Aargh! (an extended Argh! that is most likely Turing complete), the official specification, editing modes for emacs and vim, and lots of examples.
ics.el is a comint based Emacs major mode for handling the text portion of communications with internet chess servers such as FICS and ICC. It is written in Emacs-Lisp and works best in conjunction with a graphical interface such as Xboard. It handles colour highlighting and "buttonisation" (making certain portions of text active so that, for example, you can challenge opponents with a single mouse click) as well as command recall and editing and automation of commands based on regexps seen in the ICS output, all highly customisable using Emacs lisp.