A feature I thought would be incredibly useful is Location/Network Based Athan.
So for example, I normally keep the prayer times as just a text notification, without any sound as I don't want the Athan playing while I am at work, or on the train.
It would be incredibly useful if I can make the Athan play while I am at home, and automatically disable itself when I am not at home. I don't think this would be too difficult to implement.
You can use wifi network as tracking if you are at home or not, and if you are connected to the home wifi, then play the Athan.