Ask HN: Ways to make money that require lots of skill and not lots of time?

I'm looking for some supplementary income. I've taken a look at contracting in programming, but it's tough to find short term contracts where I could, so to speak, parachute in, do a task, and then disappear. Maybe I'm looking in the wrong place?

Ideally looking for responses that involve some kind of programming expertise, but I'm leaving the question sort of open ended to see what else is out there.