Real-time Transit Notifications

I'd like to develop a service that can send SMS, email or maybe Twitter messages on updates to Philly trains and flights that users can subscribe to. The service would be open to other apps to so they could add message notifications without building it themselves. Think sending a POST to this service which takes the rest from there. The app would also have a front-end that would allow you to search for a flight or train and then subscribe.

I'd like to write the backend in Node on Amazon Web Services, need help writing the front-end. Definitely doable in a weekend!

If there are other apps that could use this service, get at me and let's talk about tailoring it to your needs.

UPDATE: Not working on this during the Transit hackathon, but thinking about getting back to it in the future.