You can run this in mobile app mode on your phone or use on your desktop. Uses the HTML5 Geolocation API. I wrote this ages ago (could be improved I know) only just uploading it now.
Please change the Mapbox API key in bus.js before you use you can get one here https://account.mapbox.com/
Here is a screenshot of what to expect.
Contains data owned by TFL (bus stop locations) and uses their public API. Please don't sue :')