The Glass Armonica, invented by Benjamin Franklin in 1761. Fantastic sound. I think making one of these would be a good project for some of our local glass artists.
The Kazoo, invented by Alabama Vest in the mid-1800's. Kazoo's add interest to an orchestra, but I don't truly appreciate them on their own.
The Banjo, invented by slaves in early America, and popularized in the 1830's. Rockhoppers has a house banjo, if you want to try your hand at playing. Here's Pete Seeger to show you how:
Inventing on Whidbey Island.