Adjug

The AdJug exchange is a real-time, auction-based exchange for display advertising. Publishers and advertisers trade available inventory and advertising in a transparent environment allowing choice, control and visibility to all parties.
Publishers use AdJug:

• To generate incremental revenue from current inventory
• To gain access to unscheduled campaigns and budgets of advertisers who want to target their inventory
• To take control of which advertisers and campaigns appear around your content
• To complement their sales strategy while not cannibalising their sales team efforts
  
  Source: http://www.adjug.com/PublisherIntro.asp