Everybody is invited and welcome to contribute to Home Assistant. There is a lot to do...if you are not a developer perhaps you would like to help with the documentation on home-assistant.io? If you are a developer and have devices in your home which aren't working with Home Assistant yet, why not spent a couple of hours and help to integrate them?
The process is straight-forward.
- Fork the Home Assistant git repository.
- Write the code for your device, notification service, sensor, or IoT thing.
- Ensure tests work.
- Create a Pull Request against the dev branch of Home Assistant.
Still interested? Then you should take a peak at the developer documentation to get more details.