How to Add WordPress Plugin AJAX to the Front-End

While working on the new Treehouse Badges plugin I had to add some AJAX on the front-end of the site to check that the profile is up to date.

I found these two articles on WP Tuts pretty helpful in getting everything working:

1. An overview of plugin AJAX on the WordPress front-end
2. An example of plugin AJAX on the WordPress front-end

Thanks to Tom McFarlin for the articles!