Yes, trading using algorithms to try to make money. Emphasis on the word "try".

I love it, regardless of my level of success in it. My friend is a day trader, and he gave me one of his setups for trading. I didn't believe him, so I downloaded the data, wrote the code to simulate it across a few years, and then all of a sudden, this became a computer problem that I could try to solve through programming. I've been hooked ever since. There are a lot of much smarter people doing a lot more successful ventures than me, but for a hobby, I really do love it, and it completely reinvigorated my interests in programming.