For me it was the wait from complete to decision. I was pretty lucky that Apply-complete went by pretty fast (11 days!). Then came the 2 week wait for a decision (15 days to be exact). Seems almost instantaneous now, but at the time, every hour was painful. LOL.
By virtue of the fact that we're all applying to an Ivy MBA and we're all stressing out about it, we seem to be a bunch of goal driven, ambitious and slightly high strung individuals (
LT, the 'slightly' bit doesn't apply to you, FYI

) Waiting for something to happen would be anathema to us