In the Wiki are the following that I've used (as a publisher) or have looked at:

 - BitcoinAdvertising.com This is an adsense style service for advertisers and publishers. Publishers make money for CPC. 2% fee lowest in the industry.
 - Operation Fabulous, advertisement platform for advertisers and website owners
 - Anonymous Ads Promote your link or get promoted for BTC
 - ThroughAds Online advertising network for Advertisers and Publishers
 - theBTCNetwork Online advertising network for Advertisers and Publishers
 - FeedZeBirds - Advertise on Twitter with Bitcoins
 - Bitcoin Magazine - Advertise in the physical magazine or on the website [Update: late addition]

Wiki:
 - http://en.bitcoin.it/wiki/Trade#Advertising

(full disclosure, i hold some FZB.A / FeedZebirds "equity" on GBLSE)