If you are looking for a way to measure the effectiveness of your social media, Klout is your answer.  Klout scores measure how wide or strong your influence is in the social media world.  Scores rank from 1-100 with 100 being the highest score.  Klout ranks each profile on 3 categories; True Reach, Amplification, and Network Influence.  The True Reach is the size of your engaged audience minus all the spammers and inactive accounts.  Amplification is how often you material is passed on or if it starts others conversations.  Network Influence is measured by the Klout scores of individuals that follow or mention your material.  Read more info on the Klout website.  Klout started out by just measuring your twitter score and was incorporated in the social media dashboard Hootsuite but has recently started to include facebook and linkedin.