Having a large number of likes is a great way to drive traffic your way, but there is an economy of scale at work here that favors apps with very large numbers of downloads. Apps do not have to be huge to be successful, especially if they are providing a personal or local service, such as delivering custom-made sandwiches. In these cases, a label stating that only 12 people like something is not much of a recommendation. However, if those same people share how great their sandwich is with their friends, then we have a very powerful advertising tool at our disposal.
One of the main things that has made Facebook such a successful platform is its understanding that human beings are more interested and influenced by their friends than nameless strangers, and for small to medium enterprises, this can be invaluable. At its simplest we can simply add a share button, just as we did the like button, and this will open the share dialog. The ShareButton is as easy to add as the LikeView...