Honestly you are on one of the best sites to make passive money. (In my opinion) I posted guides about various topics about 1.5 years ago. Three of which generate the most views out of all of them. Each guide took maybe 4 - 5 hours of work after I had done research on the topic. After that I have not done a whole lot of work. Since then I have earned $500+ for very minimal work.
If you are looking for 100% passive work, you are going to have a very hard time finding it. People don't just pay for 0 work. Trust me I have looked. So far creating Hubpages is the easiest way that I have found to spend very little time and make a decent return.