A new edition of the upcoming Visual Studio 2005 will include integrated unit testing and code coverage. Go read about it here. Just to wet your appetite:
NUnit . .. but with pretty code coverage highlighting. Very, very nice; but I'm sure it's delayed until LongHorn ;)
Ok, I can live with the question-mark icons, but they had better turn into little green lamps when the test succeeds!
/Addicted to the little green lamps
Disassembling my brain