rk-todo is not a major/minor mode but a very simple function to sort paragraphs according to their first words. One can use the first word to denote something (priority, importance, urgency etc), and =RK-TODO-SORT= will sort accordingly.
You can limit the sortings effect via separators to a specific region, so it’s possible to have a “todo section” in any file.
I wrote this because I did not want to use any todo modes but wanted to have todos in my EmacsWikiMode wiki files.
I failed to work it on GnuEmacs 21.4 on debian.
Debugger entered--Lisp error: (wrong-number-of-arguments #[(reverse nextrecfun endrecfun &optional startkeyfun endkeyfun)