Teachmehowtomakearubygem is a project mainly written in Ruby, it's free.
Shows you how to make a ruby gem.
This is the repository for a gem that I live-coded for a lightning talk at @pghrb. It's a simple example of making a gem that installs a binary named teachmetomakearubygem that simply opens up the presentation I gave in a web browser.
Some revisions and video of the presentation forthcoming.