I've created a github repository add-on for Moodle. It allows you to enter your username and then browse your public github repositories. You can then select a repository, browse it by tag/branch and download the snapshot of the codebase at that point as a zip archive.
You can get the repository from the Moodle Plugins directory and I would welcome any contributions.
But perhaps more interesting for the many add-on developers out there is that this plugin is installed on Moodle.org and so can use this for submitting your add-on to the plugins database. Hopefully it will be a small improvement to the workflow in addition to the improvements which Apu is adding to the directory.