I'm very interested in this idea. Do you know of any good (preferably free) software for practicing against computers? (I used to be pretty good in high school, but I haven't played since.)

Still, do you think this is a good idea for a rationality dojo? Poker is at best a zero sum game (probably negative-sum, in practice), which seems like something aspiring rationalists should try to avoid.

Wouldn't something like day trading (where there is at least a general tendency for positive returns) be better?