I've done this before and used it for small amounts of money. More of a personal challenge than anything.

On skilljam.com you can bet on a number of different games, but it's not legally considered gambling because they are "skill games". For a good number of these you can make bots, especially the word games. Think dictionary files and a little bit of discrete math / tree traversal for some of them.

Throwing that out there! I have to warn you though, I have not used this as a main source of income ever and don't have my source anymore, but I did rack up a few hundred in a day or so and cash out no problem. I don't know what kind of detection they have running or if they even care. As my accounts leveled up the scores on some of these games became so high that I decided my bots HAD to be beating other bots.

some time back i have tried this with a german site, but they did not pay me telling i should play live at there office, to prove i realy can play so good.