There are many more websites in this category.Websites like, digg.com rottentomatos.com They made more than 10K$ with adsence/month.
Friends, Digg does not use Adsense. Digg has tied up with Microsoft. http://blog.digg.com/?p=89 http://news.cnet.com/Digg-chooses-Mi...3-6198845.html
It's just simple Logic. Follow some case studies and read some related legitimate blog everyday and do some calculations. You can also calculate such figures after some months.
any site in top 10,000 should be earning $300.00 plus a day no matter what the niche. If earnings are less than 300 a day then there is a problem.
I know site like coolest-gadgets.com or slipperybrick.com get around $1000 a day. There is a blog about the earning and history of coolest-gadgets.com by Al (the owner) at his MMO site - Selfmademinds.com (browse for the "100K site history" category). Al should be making more than 1000 a day now.