Bf.el
- A BrainFuck interpreter written in Emacs-Lisp. To demonstrate that the implementation is really working, a weird test-case is included: An interpreter written in BrainFuck compiled to Emacs-Lisp executing BrainFuck code.
- http://www.emacswiki.org/cgi-bin/wiki/bf.el

Python Mode
- Python support for Emacs and XEmacs.
- http://sourceforge.net/projects/python-mode/

PCL-CVS
- Emacs interface to CVS, the open source Concurrent Versions System.
- http://ximbiot.com/cvs/cvshome/dev/addonpclcvs.html

Phillip Lord's Emacs Packages
- Mostly additional packages for JDE.
- http://homepages.cs.ncl.ac.uk/phillip.lord/emacs.html

David Ponce's Emacs Page
- Additions to JDE.
- http://perso.orange.fr/david.ponce/

Will Partain's Collection of Haskell Modes for Emacs
- Contains eight different modes. [Dated December 1995].
- ftp://ftp.chg.ru/pub/lang/haskell/misc/haskell-modes-9512.tar.gz

ANTLR Mode
- Major mode that provides various features for editing ANTLR grammar files.
- http://antlr-mode.sourceforge.net/

ECB
- A source code browser for Emacs. It is a global minor-mode which displays a couple of windows that can be used to browse directories, files and methods. It supports method parsing for Java, C, C++, Elisp. [Open source, GPL]
- http://ecb.sourceforge.net/

Inform Mode
- A major mode to edit programs written in the Inform programming language. Supports the usual program mode functions: automatic indentation, moving over expressions, comment and string filling, font locking, tags-file support, starting compiles and parsi
- http://www.rupert-lane.org/inform-mode/

Emacs Rexx Mode
- The current version of the Rexx mode for Emacs with complete font-locking and a Rexx-debug minor mode.
- http://www.sve.man.ac.uk/General/Staff/perrin/rexx.html

PHP Mode
- Sourceforge project page of a major mode for editing PHP source.
- http://sourceforge.net/projects/php-mode/

Hugs Mode for Emacs
- Provides fontification and cooperation with Hugs, by Chris Van Humbeeck.
- http://www.haskell.org/libraries/hugs-mode.el

Haskell Mode for Emacs
- An Emacs mode currently supporting font locking, declaration scanning, documentation, indentation, hugs interaction.
- http://www.haskell.org/haskell-mode/

Ilisp
- Integration of various Lisp implementations (mostly Common Lisp systems and various Scheme dialects) within Emacs.
- http://sourceforge.net/projects/ilisp

Emacs Major Modes and Packages
- Bison and Flex mode can be found there.
- http://www.eecs.tulane.edu/www/Beuscher/emacs/elisp.html

Emacs Development Environment Tools
- CEDET is a collection of tools written with the end goal of creating an advanced development environment for Emacs users.
- http://cedet.sourceforge.net/

CC Mode
- The development homepage of the Mode for editing C/C++ and other languages with similar syntax.
- http://cc-mode.sourceforge.net/