I just found out about this wonderful site dedicated to Harpo Marx, written and maintained by his son. I particularly liked the Harpo Family Rules.
I got misty reading a lot of this. He sounds very much like a man I would have liked to know.
A largely personal blog with much silliness, Tales of the Babe & Me and of Susan the Wonderchild, lots of cat photos, and other miscellaneous stories and observations.