I remember trying this on one of my first forums when I was a teen. I set the ads up and we made a point of clicking them every day. It took forever to get my PIN to actually be able to cash in, and by the time it arrived it just didn't seem like it was worth the hassle... with all the clicking we barely got like $10. I really didn't like the idea of having ads on the site for so little money so I eventually just removed them, and haven't bothered with the idea since.