For anyone who is looking to purchase concert, sports or theater tickets, this is the best app: https://play.google.com/store/apps/details?id=com.eseats The interface is really clean as it should be and you can even choose your seat in a map of the venue, very well made. Here is the video that shows you how it works:
https://www.youtube.com/watch?feature=player_embedded&v=_IZro6TexVM