We don't do anything like this, but I sure like the idea. I hope others share what they're doing so that I can borrow/steal from their good work and yours!
I utilize views of Answered posts - this is a combination of Google Analytics and Jive data to come up with numbers that I feel strongly about. Specifically, I focus in on # of views of answered questions where the user avg's more than X minutes on page. Most of our solutions take a few minutes to digest and I think its fair to assume that someone sticking around for X minutes of time is likely finding their answer.
Once Jive has a 'this answered my question' type option for users to select, I will modify our criteria to use this.