I have some trading models and financial tools that I license. They're currently generating about $200/month, but I'm expecting that to increase within a year.

I have some trading models and financial tools that I license. They're currently generating about $200/month, but I'm expecting that to increase within a year. I'm also working on an iPhone game with two of my roommates right now that I'm hoping will bring in a couple hundred a month, but that's just a dream at the moment. The tools probably took around 80 hours. The models probably are hard to say because a lot of discovery was done over time; actually implementing them only took a weekend. The iPhone app is probably going to take around 40 hours, but it's as much a learning experience and labor of love as it is an effort to make serious money. I'm starting to focus on looking for passive income, though. I am entering a PhD program in the Fall, so an extra ~$1000/mo will make a huge difference in standard of living.