During this evenings Twitter question and answer session, I was asked about ways to measure social influence. My answer was to use Kred.com which in my opinion, is the best and most accurate tool out there.
Kred Story is a visual history of your Social Media Influence. Explore the posts, pictures and links that make you influential. See your full influence story and zoom in on meaningful moments. I will write a full post on Kred and on social influence tools in general at a later date, but for the time being have a look at this video and give the tool a try.