In Moodle 2.0 and later, the text editors can be extended and replaced by new plugins.
Join the discussions about text editors in the General add-ons forum.
Editors: HTML5 content editable editor
Replacement text editor that uses HTML5 contenteditable regions to create a simpler and faster text editor. If you find any issues, please report them on github.
Editors: Superscript/subscript editor
A very cut-down version of TinyMCE that just allows and tags. Used in some OU question types.