I want to add to what Braiam has said. Stack exchange has the following badges as reward for sharing a link with your networks: 

 - Announcer
 - Booster
 - Publicist

The Announcer badge, for example is awarded in the circumstance that you *'shared a link to a question that was visited by 25 unique IP addresses'*

If you are after more information those badges are specified on the [badges](http://meta.askubuntu.com/help/badges) section.