I don't know if this one has been mentioned before, but I didn't find it with a search. But this, to me, is very cool!
http://www.hemingwayapp.com/
Basically, it analyzes your story/sentences and grades you on "readability", as well as points out areas you might want to change.
My last "chapter" scored a 4, which is way into the "good" range!
Yet another writing resource!
Moderators: winston, another_commander, Cody