This chapter deals with MOBILE SOCIAL NETWORK APPLICATIONS GPS-BASED. As a use case we describe a Mobile Application for Android that that gives users the ability to communicate between each other and to display on a map information about important topics like road condition (traffic, checkpoints, car accidents, road work), Facebook events, Facebook Friends’ position and any other event that can happen on a road. The Application can help to reduce traffic and pollution so that it can also be considered a green technology application. The main failure of current Navigation Applications is that traffic information are provided by sensors on the road, but users must pay to access them or must check them on free website. The Application allo...