Hubspot have a great grading tool that can help measure just about everything.http://www.grader.com/
Here are some of my results. The real value of these tools I believe is the relationships you foster, the status you gain as an expert and the leads or customers that they can ultimately create. However it is nice to be able to view some analytics on how you are tracking.
I also follow my podcast to get a feel for the metrics. These metrics are important because it gives me visibility as to what is working well and what I need to focus on. Look at my tab on analytic web tools on my side bar for more tools you can use to test and measure your social media effectiveness.