Any evidence he was using Anki vs. some other? Seems like he rolled his own system optimized for Jeopardy.
http://quantifiedself.com/2011/09/roger-craig-on-knowledge-tracking/#comment-3004
Also from Final Jeopardy: Man Vs. Machine and the Quest to Know Everything, by Stephen Baker, pg 214:
..."The program he put together tested him on categories, gauged his strengths (sciences, NFL football) and weaknesses (fashion, Broadway shows), and then directed him toward the preparation most likely to pay off in his own match. To patch these holes in his knowledge, Craig used a free online tool called Anki, which provides electronic flash cards for hundreds of fields o
http://thenextweb.com/shareables/2011/11/16/mind-blown-this-guy-broke-jeopardys-all-time-record-with-an-app/