One thing people should track is mobile user agents, and the usernames they correspond to. That way when you do release a mobile app you know offhand who has an

One thing people should track is mobile user agents, and the usernames they correspond to. That way when you do release a mobile app you know offhand who has android, and who has iphone, and send targeted emails to those groups of people. Same for Google Chrome, if you wish to release a Chrome app.