.Text
.Text is a powerful blogging engine that is used to host hundreds of blogs. The application is an example of an N-tiered application. It can be used to host 1 to X number of blogs using a single IIS application. The application is written entirely in C#/ASP.NET and was built using VS.NET 1.1.

Community Server: Blogs
Community Server :: Blogs is one of the most popular and advanced blogging platforms available. Designed to host thousands of web logs on a single installation, and with a feature set desirable by every user, it's the natural choice for adding blog discussion capabilities to your site.

DasBlog
DasBlog 1.0 is a weblog engine derived from Chris Anderson's BlogX and built on top of ASP.NET and the Microsoft .NET Framework.

tBlogger
tBlogger provides a complete blog site written in C# with ASP.NET that uses XML as a backend.