For just over two years I've been teaching people how to make a full-time living writing for Associated Content. I'm averaging $140-$160 a day and my clients between $100-$120. I found Adsense to be limiting in how much you make vs. the effort involved. CPA can be profitable if you pick your product wisely and run a smart campaign. To me AC is the fastest and easiest way to get started making money online though
I use a ptc site which earns me $40 plus a day. It is all from my referrals. I have a secret to making this much for free. pm me. You won't be disappointed!