I average about $25-$30 per month. I play maybe 2x-3x a week. Average about 250-300 hands per session sometimes less. I could earn more except that I play in a home game on the weekends. I play on FullTilt so I only get 27% instead of 30% some of you guys get.
rakeback is great. I didn't realize how much I donated to the sites until I started rakeback. Last month I had over $150 in rake!