Awesome
This is the source code for Anthony's Editor as downloaded from
http://sites.google.com/site/texteditors/Home/files/Anthonys_Editor.zip
The editor is interesting as it is only 2177 lines of code and can be configured to emulate basic Emacs and Vi key bindings through a config file.
The main limitations are that only one file can be edited at a time and there is no search and replace.