CSDE (CSharp Development Environment for X/Emacs) is a full-featured mode for CSharp development in Emacs/XEmacs. Features include font-lock, indentation rules, grammatical parsing, auto complete, automatic documentation of classes, documentation checking of classes, namespace generation, using sorting, and much more. This is a conversion of the JDE for Emacs / XEmacs to CSharp.
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.
ecasound.el is an interface to ecasound from within Emacs. It allows you to use an inferior ecasound process in an comint-derived mode. It features context-sensitive completion and wizards for adding chainoperators and the like. It allows you to write ECI-based applications in Elisp.