Amplefile
Amplefile is the Contents Management System. It is windows application written for .Net environment. Using .Net remoting.

Community Server
Community Server is a rich knowledge management and collaboration platform designed to meet the demands of the most rigorous collaborative needs. Community Server is perfect for setting up a support system for products, reporting, and general information management by organizations or individuals.

DocLib
DocLib is a Web-based Document Management System implemented in ASP .NET technology.

DotNetNuke
DotNetNuke is an open-source content management system ideal for creating and depolying projects such as commercial websites, corporate intranets and extranets, and online publishing portals.  It is also a project with a vision:  to evolve its software through human participation and the sharing of knowledge.

Go.Kryo
Go.Kryo is a ASP(C#).NET simple content management system, using Microsoft SQL Server as a backend database.

Kodai CMS
Full fledged cms (Content Management System) for .NET platform. Main features of the CMS are * Scale from 1 person authored site to 1000 person authored site. * Easy to install, modular design, install only what you want and what the hosting environment permits. * Simple real life workflow. * Versioning support.

ndCMS
ndCMS is a ASP.net (C#) content management system that features a roles based user manager, file manager, a WYSIWYG editor, template manager, spell checker, search engine friendly URLs and built-in http compression. The goal of ndCMS is to provide a quick and easy way to deploy a .net website while saving you time and money.

Rainbow
The Rainbow project is an open source initiative to build a comprehensive content management system using Microsoft's ASP.NET and C# technologies.

umbraco
umbraco is a Content Management Platform written in c# on the Microsoft .NET platform. It's fast, flexible and with a user interface that makes it a charm to use. it is released under the open source license GPL.