"My Account" is the first official T-Mobile Android app which was released to owners of the G1. As its name implies, the application is designed to give you important and useful information on your account, like minutes and texts remaining for the month and a summary of your bill. If for some reason you are suffering from cellular amnesia, you can get a run down on your current plan and the cost. With "My Account" you can also access help guides and join forums. The app is available for free at the Android Marketplace and appears to be a must have service for G1 owners.
source: Android and Me