A person who supervises a ceremony.
Master of Ceremonies is the occupation, the occupation of Jay-Z and Method Man
Microphone Jockey. Read this, it's interesting: http://en.wikipedia.org/wiki/Master_of_Ceremonies
The abbreviation depends on the school and country where the degree was taken. They would include, M.A., M.Ed., MAEd., MSEd., or Ed.M.
Grand Marshal