I'm sure I say this about all my posts, but you are going to love this one. With just a tiny update to your Google Analytics code, you can understand how many people on your site user AdBlock, or any ad blocking techniques.
But, beyond that, you can also do very deep analysis of their behavior. You can understand if they stay longer or if they buy more products (or are super cheap!) or if they have a greater loyalty to you because your site experience is less sucky for them... and so on and so forth.
As you'll see from the reports and data I present for my own blog, there are a ton of surprises waiting for you.
Very little code work, a boat load of business insights away. Check my new post: http://goo.gl/fv8sbT
And, do share your feedback via comments on the blog!