Mixx dot com has been around for about a year and a half and now has a strong community of users who enjoy using their service. Now because most of its income comes from ad networks like Google Adsense (mostly Adsense) they have a little problem monetizing it.

The solution to their problem is Mixx Sifter, the best monetizing idea I’ve seen in a while, which will revolutionize the way big players like Digg.com or Twitter, will monetize their communities.

Mixx Sifter is like a separate website where users can join to review, rate and comment paid ads. In exchange, advertisers get all the information, statistics and ratings so that they can improve their ads. Mixx also guarantees that your name is secured and you can rest assured that the advertiser wont hire a bounty hunter to capture and torture you .

The best part of reviewing ads for Mixx is that they also give rewards. Every week you earn 100 karma points, which gives you the chance to win a $25 iTunes certificate or a MacBook every month.

You can see much more information on their blog and join for Mixx Sifter, a small problem is that you must be an active member.