DC Metro is a free Windows Phone 7 app that will help guide you around the Washington DC Metro. The app will allow you to find the nearest station, check on train arrival times, get directions to a station and more.
The app lays everything out nicely using the Metro design of Windows Phone 7. Hub page also include a way to check up on the most recent disruptions, tweets, and news items published by the metro authority. You can also monitor things via Twitter through DC Metro.
You can download your free copy of DC Metro here (opens Zune) at the Marketplace.