Sitefinity
Sitefinity is a powerful CMS platform offering many enterprise features, and simple, easy-to-use online administration for managing your website. The new revolutionary User Interface is very task oriented and simplifies the user interaction with the system.

DotNetNuke
DotNetNuke®, the most widely adopted web content management system (CMS) and application development framework for building web sites and web applications on Microsoft .NET. Using DotNetNuke, businesses can quickly develop and deploy interactive, dynamic public web sites, intranets, extranets, and web applications.