Folks using MbUnit

• SAS Institute
• The Health Care Practice Area of Northrop Grumman
• Danish Institute of Technology
• American Idol Underground
• Insight Direct, Inc.

Opensource Projects

• http://www.icsharpcode.net/OpenSource/SD/Default.aspx
• Gentle.NET
• http://www.subtextproject.com
• http://subsonicproject.com/

and more...