Here are some good Open Source ASP.NET Web CMS that are popular in the community. You can Bookmark this link for future use
N2 CMS - N2 is a lightweight CMS framework to help you build great web sites that anyone can update. Using it's interface is intuitive and empowering. It is based on an object model with separation between view templates, content model and database and integrates well with the ASP.NET and ASP.NET MVC 2 paradigm.
DotNetNuke Community Edition - DotNetNuke, also known as DNN, is the ideal platform for building professional websites with dynamic content and interactive features. It is the most widely adopted Web Content Management Platform for building web sites and web applications on Microsoft .NET.
mojoPortal - mojoPortal is an extensible cross platform, cross database, content management system (CMS) and web application framework
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