Before, I didn't think doing PTCs (or paid to click) would be profitable. However, now I can see that you can actually earn a decent amount for it. This can be done by working with several PTC sites at once. Of course, you have to make sure that those PTC sites are legitimate by looking around the blogosphere or searching for information about the site in Google.
I've already signed up for 9 PTCs, and am currently looking for other sites that really pays its members. I wrote an article entitled Paid to Click Sites here, which features legitimate companies I've researched.