Other
The Virtual Museum of Music Inventions
The title is misleading, for a reason! The site consists of tips, ideas and plans about instruments and sound. The site also serves as a "museum" for photos and audio/video clips of kids' homemade instruments from around the nation.
Other
Oddmusic
You will find many creative and imaginative musical instruments on this site. If you are creating your own instrument you'll be inspired by what others have invented.