I think the amount of ads on a page depends on how you lay your page out. For example some sites have one and it can be extremely annoying and can get in the way. However on daniweb (on the page I am on) there are 6 ads and I don't find them annoying because they just work with the page perfectly.
Adf.ly is the best CPM program...with average rates of $2 and U.S exclusive CM of $2.7.. with lifetime referral of 20%...click on this to find out & register... http://adf.ly/?id=32557 I stopped using Adbrite,Chitika and Infolinks after adfly
through another blog, i found out about altitudedigitalpartners.com and they had the highest CPMs that ive used thus far. even higher than most of the top networks we have used in the past. plus they paid on time