Emacs is a project mainly written in Emacs Lisp, it's free.
My emacs config
This config is designed to work with Cocoa Emacs 24
(Heavily influenced by https://github.com/mig/emacs.git)
$ git clone git://github.com/pithyless/emacs.git ~/.emacs.d
$ cd ~/.emacs.d/ && mkdir el-get && cd el-get
$ git clone git://github.com/dimitri/el-get.gitBe sure to run package-refresh-contents before doing anything else.