Johnbai's diary a ways down about Sean Green got me searching through the gameday logs looking for how much he's used his slider versus his fastball.  
Nothing systematic - just a quick look.   I love that we've got this data source, but I'm not really going to be the one to mine it and turn it in to something useful.

Well, lucky for me, this guy did.  
What John Kalk's got are charts for every pitcher who's thrown over 100 pitches in an enhanced gameday park.   You can see what they throw, and get a rough idea of how much they rely on one pitch or another.  I think it kicks ass.

He's developed an algorithm that classifies pitch types using the pitchfx data.   For many/most, it works beautifully.  The aforementioned Mr. Green is one of these (as you'd guess).   But he'd like some help if the formula's just obviously missing something - if the pitch type is wrong (splitter as opposed to slider), or if there are a lot of 'unknowns' that fans might be able to shed some light on.   So check out this list, and let's see if there are some anomalies.