I stumbled onto this site after reading another writer who had subjected his own writing to this test. It is pretty simple and quick to use. Click on the first link, cut and paste your sample into the box, and submit whatever writing you choose. http://www.standards-schmandards.com/2005/measuring-text-readability/
Interestingly enough, I submitted 15 blogs from my site and a few other bloggers. The ranges were a grade level (5) Knuckledraggin My Life Away (stolen truck block) to a grade level (17) at naked capitalism. My scores were between 7 and 12.
I even submitted an Obama campaign speech (text, obviously) in 2008. It scored at the eighth grade level.
Oddly or not...I liked Kenny's piece the best. Grade level 5. I had a promising future back then.