Panic's Status Board is a really awesome iOS app for Status Board making. I wanted a simple way to add arrival data for my nearest Metro stop to my Status Board. This is that way.
Spelled out in requirements.txt, but summarized here for your enjoyment:
Flask
Flask-Bootstrap
Requests
Gunicorn is an optional dependency, if you want to run the app on Heroku.
Other than the standard setup for Python webapps (virtualenv, installing from the requirements file), you must export the WMATA_API_KEY enviroment variable for use inside the app. The API key can be obtained here.
Right now, there is no caching of calls to the WMATA API. Depending on the amount of traffic this recieves, some caching may be in order.