my site is PR5, 10+ months old, completely original content every day, it makes more money from selling ads then it does through adsense.. but its almost to the point where im going to yank adsense all together. i ended the day making $1.57 on 41 clicks. yippy!
try gg ads preview tool to see what ads display in your site. Maybe you'll find most site in that is MFA. Hope this help.