I'm developing free one: http://AdSenseASP.NET/2.0-WebControls/ - ASP.NET 2.0 web controls library for Google AdSense. Consists from AdSense AdUnit, AdSense Link unit, AdSense ReferralUnit ASP.NET web controls.
There is a live demo on the web site: http://AdSenseASP.NET/Sandbox/ so you could take a look to the web controls functionality before downloading.
The diffference to others is that it has configuration module so you could configure parameters like Google AdSense PublisherID, AdSense channels, colors, etc on by per website basis. So you don't need manage it for each page and web control.
So you could give a try to my http://AdSenseASP.NET/ library.
Let me know if you have any thoughts - will apreciate any feedback.
More about me at http://sharp-developer.net/CV/