Bitvisitor is another site that I recently found where you can earn Free Bitcoins.
All you need to do is enter your Bitcoin address, and view each site shown to you for 5 minutes. The sites that pay the most go first, and you then work down to the least paying sites. You cannot view the same site twice, so you can view all of the adverts until more are posted. From what I can see though, many new ads are posted every day.
If a site advertises their self on there for, lets say, 250 viewers then you cannot be part of that 250 twice. But if they advertise themselves for a second round, then you can view that.
Overall, I give this site a 8/10. This site has a very good system and pays almost instantly, with a very nice, simple site design.