Great article on NUnit and Unit testing: http://www.theserverside.net/articles/article.aspx?l=UnitTesting

Visual Studio Add-ins for NUnit

• http://www.testdriven.net/ - TestDriven.NET works with Visual Studio 2002, 2003 and 2005. It supports the NUnit, MbUnit and TeamSystem test runners. It has robust support for executing and debugging tests out-of-proc -- JamieCansdale
• http://www.mailframe.net/Products/TestRunner.htm - aparently this doesn't work very well.
• http://www.relevancellc.com/vsnunit.htm - The author Justin Gehtland has pulled the plug on this project.

I had some trouble running NUnit V2.0 GUI test runner with the FlexWiki dll. Once I upgraded to V2.1 the GUI test runner worked fine with FlexWiki the dll. -- MikeLinnen