Finally, a competitor to AdWords. We stopped using Google AdWords a couple of months ago when, in their infinite wisdom, decided that we were not following the terms of their service when we put Google banner ads at the top of our Community Edition product. It seemed like a really dumb thing to do considering that we paid Google 10-times more for the AdWords service than we received from their AdSense service. Part of the problem is that Google provided no details as to why they were shutting us down, nor was there any dispute mechanism to help us understand the issue and correct the problem. The funny thing is that our sales have not dropped since we stopped using Google AdWords.
In any case, we are going to experiment with Microsoft Advertising and we encourage you to check them out as well.