If you are looking for a free ASP.NET blog engine for your company or personal website, dasBlog looks like the king of the hill now. I will be installing it for a new blog in the next couple of days as a marketing tool for a new business.
I am thoroughly excited about all the performance ehancements and new features that have been added to the newly released version 1.7. dasBlog is open source and free to use for your websites.
Here is a post by Scott Hanselman on the new release.
You can download dasBlog from SourceForge here.