Let me add to your list
Epom.com - quite high paying cpm network. From reviews, they are well-performing in the US and LATAM traffic.
Edomz.com - another high paying network, decent supplier for EU traffic.
Nrelate.com - content discovery network - best for the entertainment networks, there are tons of awesome websites with this topic in their network.
Nster.com - buy, sell, exchange traffic with great rates (150%+ return rate).
Specializing on the U.S. traffic. Content wise, they pretty much balanced (have more than 10 content categories)
Outbrain.com - big folks with good traffic (tons of it), but who charges ridiculous commission. If you have a news portal and some cash - might want to check this out.
Nrelate.com - another content discovery platform. A bit expensive for specializing in entertainment though.
Content.ad - small but proud network. Quite a good place for PPV increase.
Zemanta.com - buy, sell, exchange... if you have a blog. Couldn't figure out how to make it work for the website.
Taboola.com - buy or sell - are only options here. Decent small ad network.