The San Fransico Transportation agency, BART , is using an augmented reality application called junaio to help improve the experience of its travellers. Transit riders can use the application to navigate their way to stations and stay up-to date with the latest train schedules. This is a practical application of augmented reality, something that has mostly been used for entertainment purposed so far.
By pointing a mobile phone at BART signs, users to the Bart channel (powered by junaio). BART was one of the first transit agencies in the US to provide real time data to developers, resulting in a number of applications for its clients. On top of the augmented reality functionality users can also take pictures and notes and leave them behind as virtual breadcrumbs on their location. Users can then pick up these notes by simply pointing the phone. The app can be found here: http://www.bart.gov/apps. Check out this demo: