I want to get something similiar capped around 80 hours a month. I found that position by talking with the founder for a year on angellist after he went through a number of cheaper php employees he needed someone to solidify the code base and add in advanced features. Once that was done he was able to go back to younger and cheaper.
I would never do it now, I couldn't squeeze in the time between working full time, exercising, spending time with my family, and just keeping up with technology.
At some point, the marginal utility of extra money doesn't mean that much. I'm by no means rich, but extra money wouldn't change my lifestyle.
eg Moonlightwork sounds like it should be for moonlighters like this, but looks to be full time jobs.
More details: One of them was a bakery that was taking all its orders on paper, so I developed a simple but powerful system for them to track their orders in a database, and other was a small investment shop(read: a pair of people managing a millionaire's money) who were looking for a way to track trades and get on with the important stuff rather than waste two hours a day updating an Excel spreadsheet. My biggest problem I haven't been able to leverage these jobs into continuous passive income.