Back in the 80's, I used to love to see the NBA slam dunk competition, especially when 5'7" Spud Webb would compete in them.  Check out this video of 5'5" Porter Maberry performing and Eastbay dunk.  Thats a dunk in which a player catches the basketball, puts it in between his legs and dunks it..

I'm not sure if Porter is the shortest player to do this dunk, but I wouldn't doubt it.  Check out the amazing dunk below: