I've had clicks vary from $0.05 up to $1.20 per click on the same site, same day with the same content. It probably has a lot to do with the quality of content AND visitors to your site. I have noticed that visitors that arrive via search engines are earning me more per click.
YPN isn't like that anymore - I think that was all still in the early stages that people got payouts like that...
Today i have 7 page impressions and only 1 click for $1.56. I broke a new record. I cant imagine for tomorrow.