Why not be one among the opinion providers for research companies? As these surveys are an important source of information, they are paid well. You can be the part of their opinion survey and can be assured of getting some good income. Let me tell you these surveys are paid based on the complexity. I as starter limited myself to 2-3 surveys a day and increased later on. I don’t say that the field is free from scam so; you should be very careful in choosing the companies.
I personally like this one for some spare cash. It does not take much to earn an extra $20 – $50 a week. Some claim that they are able to make a living by dedicating their time to different jobs at mTurk. You will have to go through a learning curve, but once you get comfortable, you will find plenty of good and interesting HITs (Human Intelligence Tasks) to work on.