Emacs
Xplain-mode
I've created an Emacs Xplain mode: xplain-mode.el. This brings you Xplain aware editing with syntax high-lighting.
Eiffel stuff
I've written some extensions to the Eiffel emacs mode that make it work better with Gobo. Use this Emacs file to load and configure the Eiffel mode.
Guido-mode
I've created an Emacs Guido Music Notation mode: guido-mode.el.
ConTeXt mode (obsolete)
ConTeXt support is now integrated with AUCTeX. I'm maintaining and supporting this part of AUCTeX. I suggest you start using AUCTeX instead of downloading and using the package below.
In case you do not want to install AUCTEX, you can still use my ConTeXt Emacs mode: context.el. This mode extends tex-mode.el with ConTeXt specific features. See the context.README file for installation instructions and Emacs tips.