<p>Can anyone recommend any Ad Management components for .NET?  I have a customer who would like to sell his own advertising through his own site.  This rules out using packaged ad providers such as Google Ads.</p>

<p>I've googled several packages, but I'd like to see if anyone has any first hand experience with a particular package.</p>

<p>Or should I just roll my own ad management system?</p>

<p>Thanks!</p>

If there is going to be any size or complexity to the ad system, I wouldn't roll your own.  Focus on your core competencies and outsource the rest, because ad people can be crazy and it's nearly impossible to implement all the features they would want.  Frequency capping, geotargeting, failover reporting, inventory management, just to name a few.
Check out Atlas Solutions, formerly Accipiter (now bought by Microsoft), which provides hosted ad serving solutions.  Of course, that will come with a price, but what doesn't?