NOTICE: This plugin is still in alpha and not ready for production use. Use at your own risk.
I found this plugin really useful. I downloaded the master zip file, uploaded it as a plugin, and now I can search both GitHub and the WordPress.org plugin repository, for plugins.
This plugin uses the GitHub api to search for files that have the WordPress plugin header, then allows you to install them directly to your WordPress site without having to download the zip, then upload it.
To get the plugin, first download the zip.
Here’s a video, showing how to search GitHub for WordPress plugins.