If you haven't tried Klout yet, it's addictive. Klout provides a score based on your social influence using the sites you interact with such as Facebook, Twitter, LinkedIn and Google+. The Klout Score ranges from 0-100, with 0 meaning you have no influence, or haven't provided Klout links to any of your social profiles.
When you sign up for Klout, the software will ask you to sign-in to any social sites you belong to. Depending on your score, the Klout may advise you "to engage more with others or be more active to gain influence." Simply put, the more social engagement you have the higher your score.
Currently, Klout says they are working on measuring the influence of additional well known sites such Youtube, Instagram, Tumblr, Blogger, Wordpress, Last.fm, Flickr, and Facebook Pages. For now, you can just link them to your account.
But Klout may not be for everyone. Do you want one web service having access to all your social profiles? And, until the service adds Facebook Pages it may not be useful for web marketing consultants looking to leverage a business's social impact. The software is most useful in measuring your own influence. Along with your morning coffee, enjoy daily statistics (generated overnight) about how far your audience reaches.
UPDATE: August 7, 2020
What Happened to Klout.com? Find out in a post written by UAT alum Adam Carter's company here: https://theproductmanager.com/general/what-happened-klout/