Contextual ads : Media.net (in some cases better than AdSense), Chitika
CPA banners : Peerfly
CPM banners, native ads in some niches : Amazon
Native ads : Content.ad (low traffic) Revcontent (high traffic)
pop ups, pop unders, lightbox, interstitial (mobile) : ad-maven
intext, inframe, increen, inarticle: Infolinks