I'm beta testing the new P.I. feature at Baseball-Reference.com. So far I gotta tell you it's really cool. For instance, Mariano Rivera has recorded 199 outs on comebackers in his career. That includes four in one game on 5/15/04 against Seattle, as well as Jay Gibbons on three consecutive days (8/14/03-8/16/03). And Rivera has 135 game-ending strikeouts.
Still testing this stuff out, but there's sure to be more wicked awesome stuff to follow.