Mapnificent (http://mapnificent.net) was developed by Stefan Wehrmayer, and was “inspired by Mapumental”. The application can parse GTFS data to show travel time maps to destinations in multiple cities around the globe, and is currently free to use.
The results are displayed with Google Maps.
The first version’s source code is available, whilst the developer claims later versions will be published soon.
Credit to Appropedia for the initial content.