I have seen lots of banners on different pages that looked like was placed through rightmedia.com. Visited that website but didn't find place to register as an advertiser.
if your seeing rightmedia,it may they are using https://direct.rightmedia.com/.you can only join that if your an ad network. use the contact forum at www.rightmedia.com. rightmedia.com is part of yieldmanager.com.
We're a member of the Right Media Exchange. Send an email to info@kitaramedia.com and we'll have someone contact you. Thanks! Brad