Not sure but I have noticed, me and another friend, that we have been getting alot of cpm banners showing on our sites, pay seems to be low. I get more from Ads for Domains.
I was about to post new thread regarding this topic.... Can we place ads from adbrite, bidvertiser along with google adsense?
"Make sure they are not contextual." What do you mean exactly? I am thinking about image banner ads. But I think most of today's CPM Networks do match the banners to the context of the pages. Will that be fine?
there is no such rule anymore,so that doesn't apply. you can use cpm ads on your site,but pick a good network. ads from a cpm network is content on your site and they have to follow the same rules,so avoid ads with gambling,tobacco,alcohol,ect...