Another question asked why there are so few non-vi modal editors. A few of the comments in that question mentioned other modal editors in passing, but I think that it would be useful to develop a more comprehensive list. Searching for this information on Google is difficult, as vim-related information tends to drown out everything else.
A few items to get things rolling:
There are so few modal editors because:
a) they are a PITA to learn.
b) it was a solution to a particaular problem (getting a WYSIWYG error to work on a generic low function terminal) which does not really exist any more.
With a modern GUI (or indeed a 3270 terminal) you only need to provide a test box or specific screen area for command to achieve the same effect.
Because modal editors are evil? (Someone add an EMACS tag to this.)
"why there are so few non-vi modal editors"
I think it's reasonable to conclude that vim is so incredibly deep and extensible that competing with it (attempting to make a comparable modal editor) would be extremely counter-productive.
There have been many Non-vi modal editors over the years. Many of them tied to a single operating system.
WordStar, edlin, and ISPF come to mind. Also EDIT from the HDOS system. There are probably at least a dozen others named EDIT or it's variants.
I've never tried it, but AFAIK Emacs has a plugin to emulate vi's modal editing.