I noticed some of the sites gets $1-3 cpm rates on adbrite, How is that possible does cpm increase itself ?
I can't comment on the specific policies of AdBrite. However, it seems that AdBrite is structured around a policy where direct ads can be bought through AdBrite. These sites probably provide a good ROI, are in niches that are performing well, and have a good direct ad sales team, or have their AdBrite ad sales link prominently placed. CPM's are paid by the advertisers, so if you want to increase your CPM rate, ask yourself what you would want from your site if you were advertising on it.