This is a simple module that does lets you display the contents of a directory inside the control panel, and link to it by creating a new control panel tab. A client of mine needed some documentation on how to use the site, and I wanted to make it easily accessible.
There is an accompanying extension that lets you set the directory in which your documentation resides. The module itself just displays the contents of said directory. For example, I set my directory to /path/to/my/site/documentation, and the module looks for an index.php file within that directory. From there you can do anything you want.
http://brianlitzinger.com/assets/downloads/ee/documentation_1.1.zip
