Eproject-peepopen is a project mainly written in Emacs Lisp, it's free.
The peepopen emacs plugin ported to eproject
eproject-peepopen.el is a light-weight alternative to TopFunky's peepopen.el (https://github.com/topfunky/PeepOpen-EditorSupport), which depends on the presence of textmate.el for basic functionality.
eproject-peepopen uses jrockway's eproject.el to provide the same PeepOpen integration without introducing any of textmate.el's extraneous functionality.
If you don't already have it, install eproject.el (https://github.com/jrockway/eproject)
Add the following to your emacs config file:
(add-to-list 'load-path "~/.emacs.d/vendor/eproject-peepopen")
(require 'eproject-peepopen)