I occasionally sign up for psychology experiments that pay $10-14/hour. There are always a lot of experiments going on at my university, and I usually get first dibs because I'm a research assistant. With a lot of normal part time jobs, regular hours are expected. But with this, you can schedule hours that are seemingly weird for jobs but work out for you, and there's very little commitment and a great amount of variety. I think I end up doing around 8-10 hours worth of experiments per week.