Klout
Klout is a metric for overall online influence. Klout gives a score ranging from 1 to 100 with higher scores representing a wider and stronger sphere of influence online.
Klout uses over 35 variables on Facebook and Twitter to measure True Reach (the size of your engaged audience - only including active accounts), Amplification Probability (the likelihood that your content will be commented on or retweeted), and Network Score (the influence level of your engaged audience).