Sometimes play multiple tourneys at once. Again I dont like more than two and think Jezza's comment about the physical positions of the windows is a very good point. I always move one towards the top left and one towards the bottom right to prevent clicking a button on the wrong table when the software changes tables.
Talking of high stakes multitabling, I remember seeing Phil Ivey(think it was him) playing 2 high stake cash games and 1 medium at the same time on
Ladbrokes one night.