Well, I am a year and a half late with an answer.
I have recently completed writing an app for the London Underground. Its sole purpose is to display the real-time train arrival times for all platforms of all stations.
It also displays the London Underground Map. There is a small delay every time one asks to see the map, as I can not store the map on the android phones without paying a substantial royalty payment to the TFL. So, instead the map is downloaded every time from TFL's website and displayed in an Android webview which is sort of like a web browser but under app control.
One chooses the rail line to be displayed, like Bakerloo for example, and one sees all the stations and platforms on that line in travel order in a scrollable area. Fresh prediction information is fetched from TFL's website every 30 seconds.
What is unique compared to other apps, is that it displays many stations at once. Also, trains arriving at ALL platforms at a station are displayed even for other rail lines. This is helpful when you are planning to transfer to another platform at a station, as you can readily see how long you will be waiting for the transfer train without any need to traverse menus.
I wanted to add more color, but thought it best to publish it before the Olympics begin.
The app sells for approximately one pound on the Google play store. I would like to allow a few people to use it for free for a few months on condition that they provide me with feedback. Hopefully, these people will like it and will provide comments to help make the app better.
regards,
Howard