Official maps from the MTA, updated and movable to the SD card. The app downloads each bus map the first time you open it. Each bus map weights around 2 MB, so I recommend downloading it through Wifi and waiting a couple of minutes. If a map doesn't download after giving some time, try performing an "empty cache" through the applications menu in your operating system settings.
Users with Android versions prior to 2.1 might experience errors.
Popup ads were removed long ago, as a response to feedback. Double banners are a bug, please let me know if it persists after update. Send me your suggestions and I'll try to add/fix them.