This is the best thread idea since the season began (I would say.) Great question.
Obviously Fab 5 would have to be one; along with the 1997 season. How about last year's hockey season? I know Michigan didn't win, but when you take a look back, what a remarkable run to actually qualify, right?
EDIT: To add, if we were to focus on individuals in Michigan sports - John Navarre (for the abuse he took from fans), Zoltan Mesko (remarkable story) and Juliana Paz (another remarkable story.)