Wow! What an awesome list! My favorite is the stock photography because I love photography. I have had some success there, particularly with one photo I make some decent income from. I think the key with stock photography is finding a shot that is high demand. Then, find a new unique way to frame that shot. This is the reason my St. Louis Arch photo is a top 10 on both ShutterStock and iStockPhoto. Thanks for the awesome ideas above!
Another benefit of residual income is that, if the income stream is large enough, one does not need the main focus of his life to be on making enough money to survive. Having a comfortable and continuous level of residual income opens up more opportunities to travel, look into other business opportunities, and even take the time to indulge in his hobbies.
Residual income is really the best Way of Life. It's a steady, reliable stream of income not directly dependent on the hours you work. Successful investors enjoy such freedom. Successful book authors get paid even when they don't write. The checks just keep coming uninterrupted, even when you relax. This is much better than hourly work. Much better that salaried work.
There are many people who get paid vast amounts of money to become the CEO of a company, play professional sports, or star in a movie. Earning a high active income is often a lot of hard work and requires a dedication beyond most of us. It’s also limited because no matter how much money you get paid you still need to show up to work to earn your money.