Meh, The Melbourne Cup stops a nation, the Superbowl just stops people who want their yearly fix of NFL.
Soccer

World Cup biggest event, Olympics Second, Rugby World Cup Third.
Far as best IMO...Rugby World Cup...slightly oneyed though.
World Cup is pretty much the only time I'll watch soccer, or make an effort to watch it (will happily get up to watch the Socceroos beat England in the quarters).