Probably the Steam app. While it doesn't have any games, it lets me talk to my Steam friends and also buy games in case they're having a sale and I don't have access to my PC
I think steam is great. I love it since it eases and smoothens my experience in playing games. It a bit wonderful that none one can assess my account unless I permit them to. This is because it offers a login in platform where you can login using your particular access code which may not be applicable with anyone else. I just downloaded it on my Android and it is really doing well.
