Andy Carlisle's William Henry Harrison Web Page. The first President Harrison served only a little more than a month before dying. Not surprisingly, there is not a ton of material online about him.
Any Carlisle has a site up at Homestaed.com that has some basic information. The facts appear to be from an old copy of The Book of Presidents.
From the site:
He was the only president who had ten children.
He was the only president who studied medicine.
He was the first president who was a professional soldier.
He was the only president who served as territorial governor.
He was the only president who served as minister of Colombia.