After months of off and on searching I finally found the XML data that MLB.com's Gameday uses. In other words, any information that's available on Gameday can be put into a database that I can easily search.
Do you want to know how often Juan Pierre hits a fly ball on pitches out of the zone against Armando Benitez on an 0-2 count in San Francisco? Soon, I'll be able to tell you.
You can easily measure how much of a geek you are by how excited you got by that last paragraph.