Biggest Badass in Jeopardy History: Roger Craig
Adam Rifkin stashed this in Best Videos
The true daily double became Roger's "thing" after this, and he ended up losing the first game of the two-part Battle of the Decades tournament finale against all-time champs Brad Rutter and Ken Jennings (who pressured him into betting it all) because of it. Then on the second day he did it again--with the exact same amount of money.
And as a bonus, here's the clip of his final score in the game in the original link. It's the highest total for a Jeopardy! game ever:
Roger Craig's presentation on how he used statistics, programming, and knowledge tracking to optimize his jeopardy knowledge and gameplay.
He basically managed to quantify his own performance at Jeopardy in order to improve his game in a way that let him track his improvement with actual numerical data rather than just a "I feel like I'm good at classical architecture but not so good at renaissance painters."