[johnny]

Technically, the shortest "song" on my iTunes is the "Nutopian National Anthem" by John Lennon, but it's four seconds of silence so it probably doesn't count. xD

Then I have "Miracle Cure" by The Who, but that's a sort of bridge song for a rock opera album called Tommy. Also not sure it counts, but it's thirteen seconds.

"Her Majesty" by the Beatles is 23 seconds and we're getting closer to actual "song" territory, here.

"Maggie Mae" by the Beatles: 41 seconds.

"Tea for the Tillerman" by Cat Stevens: a minute, two seconds.

I have about 60 songs under a minute and thirty seconds, at varying degrees of completion.