There are several ways to make money online. Some people go with pay-to-click sites, which are easy to start using, but hard to make real profit with. Being a poker/casino affiliate is a good option, but the competition is though, so you really need to offer something unique that graps peoples attention. Below are links to few of the best poker affiliate programs at the moment. But you really need to do good advertising to get the money flowing.
Full tilt affiliate program
Betfair affiliate program