How to write a simple Rails gem

Today, I wrote my first Ruby on Rails gem.  It was a very simple refactoring of our code that I undertook when I needed to add the same functionality to a new model and I decided to do it as a gem instead of keeping it within our project.  I wanted to see how it worked and this is what I ended up with.  You can follow the Rails Guide, but it didn't cover everything I wanted to do.