As far as roulette goes, I believe that casinos changed the rules a long time ago to require that the bets be placed before the ball is released, after a group of UC Santa Cruz physics postgrads in the late '70s, early '80s built a wearable computer that would predict which octant the ball was going to end up in well enough to give a 44% advantage over the house. See: <a href="http://en.wikipedia.org/wiki/Eudaemons" rel="nofollow">http://en.wikipedia.org/wiki/Eudaemons</a><p>What you could still do, though, is use the computer to look for biases in the wheel. Roulette wheels do not produce uniformly distributed results, and with enough data you can find bets that give you an advantage.<p>This was covered in an episode of the wonderful TV series Breaking Vegas ( <a href="http://en.wikipedia.org/wiki/Breaking_Vegas" rel="nofollow">http://en.wikipedia.org/wiki/Breaking_Vegas</a> ). Each episode of that series focused on one person or group that found a way to beat the house. Some cheated (bribe the dealer, hack the slot machine software, sleight of hand to alter bets after the outcome is determined), some develop amazing physical skill ("dice dominators" can throw dice with such precise control over the initial conditions that they come up with the same outcome each time), one guy counterfeited casino tokens (and did such a good job that the chip manufacturer was not able to tell which tokens were his and which were theirs--they only knew counterfeit tokens existed because more tokens were coming back when they emptied the slot machines than they had issued), and some (such as the roulette bias people) exploit the math of the game.<p>In the episode that dealt with roulette biases, there was a family in Europe that would observe a wheel for a very large number of plays, taking notes on the outcomes. The casinos do not object to note taking--they encourage it, because people taking notes are people who think they have a system, and 99.99% of the time people who think they have a system are people who do not understand the laws of probability and are going to lose. Well, this family is not part of the 99.99%. They took their notes, found the favored numbers, and bet on those, and won big.<p>The casinos tried moving the wheels between tables, but the family members had spent so much time looking at the wheels gathering data, they could recognize the wheels from wear patterns, scratches, and so on, and so still place the right bets.<p>The casinos then simply banned them. If they had been playing in Las Vegas, that would have been the end of it, but they were in Europe. They went to court--and the court said casinos could not ban people for simply winning too much. The family had not violated any legitimate casino rules, so the casinos had to let them back in.<p>I don't remember how the casinos finally stopped these people--probably by replacing wheels with ones the family had not seen, or physically altering the wheels to change the distribution.