Hello,

Here are the most viewed adCenter API topics on MSDN for June 2009.

Microsoft adCenter API Version 5.1 (Start migrating to V6 and use Microsoft adCenter API Version 6 instead !).
Microsoft adCenter API Programming Reference
Microsoft adCenter Campaign Management API Reference
Microsoft adCenter API Release Notes 
What's New in the SDK for Microsoft adCenter API
Microsoft adCenter Reporting API Reference
Campaign Management Data Objects
Campaign Management Service Operations
Developing with the Microsoft adCenter API
United States

Thank you.

Walter Poupore
Developer Content Manager
Microsoft