You'd like to contribute? Great! Just a few things to be aware of.
Please add tests for any additions. You'll need your own MailChimp account (free) and will need to modify the mailchimp.config that is created for you from the template when a build is completed. In this file, you'll add your api key and a list ID that is called MasterListId.
Good luck and thanks for helping out! If you run into any problems, please submit an issue.