In addition to what Braiam said, stack exchange has the following badges as reward for sharing a link with your networks: 

 - Announcer
 - Booster
 - Publicist

As an example Announcer is awarded in the circumstance that you `shared a link to a question that was visited by 25 unique IP addresses`

More information on the [badges](http://meta.askubuntu.com/help/badges) section.