I only see some sites that offer exact rates on what they pay, and some don’t even tell you until after you have been hired. I would rather get an idea if the work will pay for itself or not. Some places I think just expect too much for too little (information) upfront.
Online jobs aren’t easy to come by. I’ve been trying to find a few different jobs to help out. Writing jobs seem to be the easiest to come by. You can also do the Google rating jobs. Some customer service phone jobs can be very flexible as well.
For a student you would want a company where you can log in and out at will and have a great deal of control over the workload. Freelance writing sites and sites with micro jobs like Amazon Mechanical Turk and Micro-workers would probably be best.
Students can join online focus groups. Focus groups are needed while coming up with new products. Some companies pay participants good amount of money. A student can register with survey sites so that he can make money taking surveys. A student can also find time in the evening and do freelance jobs.