I just finished reading Bringing Down The House, the non-fiction book that inspired the movie 21. It's a pretty easy read, and fairly entertaining.
It's pretty fascinating that Blackjack is actually a beatable game, provided you're really good at calculating on the fly the probability of getting good cards. What's hard is that you need to play a lot to get it right, and it's something these kids could do because of their team system. I can barely play poker, let alone track all of the cards going in and out of various hands. What they did was not gambling. I never knew that card counting (which is not really what you're doing) is totally legal, but you can be sure they'll kick you out if they think you're doing it.
The story is a little slow in the middle, but the most interesting parts are really the way they get sucked into the lifestyle that all of that fast money afforded them. There's no doubt that it changed some of them, and not for the better. You also get an appreciation for parts of Vegas will (thankfully) never see.
The movie barely has any real connection to the book, other than the notion that some dude put together a team of smart kids from MIT to play. The lead characters were all half-Asian for starters, and the significant female was actually married to one of the other spotters on the team. Don't get me wrong, I enjoyed seeing Kate Bosworth slink around in a tiny dress with a little black wig, but I think portraying them more closely to reality would've been more interesting.
I think the most winpossible (yay for word invention) game is poker, because you're up against humans, and someone other than the house has to win. It's still a long shot, but again, if you play based on probability, throw in a little human factor understanding, a lot of practice, your odds are likely better. I tried it last time I was in Vegas. I probably would've done better had the alcohol not been flowing so freely!
Give the book a read if you're looking for some OK non-fiction narrative.