I've never bothered with gambling - other than as paid entertainment with the occasional refund - but if I did, seems like sports betting is the logical place to go. As a statistician, it's pretty easy to see why most casino type games are a losing proposition, but the way betting lines move intrigues me. I think if you limited yourself to betting on favourites where the lines get significantly moved by sentimental underdogs, you could probably do pretty well. You would just need an environment where events like that happened regularly enough to take an advantage of a (probably small) positive expectation value.