Rockstar Games has created an app to accompany the blockbuster title, Grand Theft Auto V. This app can be used to access features such as Rockstar's Social Club, Lifeinvader (their spoof Facebook) as well as access other games that contain Social Club functionality. You can even use the application to customize cars.
The app also allows you to feed and play with Chop (Lamar's rottweiler), Franklin's companion. This will improve his happiness, making him more likely to attack your enemies and obey commands.
This is actually an awesome application and can easily affect your performance in game. However, Rockstar is experiencing issues with their servers. I was able to log in only for a few minutes last night and again this morning. I was able to feed Chop, train him to sit then in the middle of helping chop find love I was kicked off.