There are several attempts -- some more, some less successful -- to refactor, improve, and extend Emacs as a platform and editor. (One of the more interesting ones, in my opinion, is GuileEmacs, which is an attempt to use Guile Scheme as a replacement for Emacs Lisp.) Here is a good list of things you might be looking for:

http://www.emacswiki.org/emacs/EmacsImplementations