Quaver's
Note Names
Smithsonian's Star Spangled Banner - Learn all about the history of The National Anthem and the original Star Spangled Banner. Has an awesome interactive flag section.
New York Philharmonic
SFS Kids Instruments of the Orchestra
San Francisco Symphony Kids
Dallas Symphony Orchestra Kids
Oregon Symphony - Instruments of the Orchestra
Lots of music games!
Young Person's Guide to the Orchestra
Are the musical clips the same or different?
Robbie and Curly's Musical Mysteries
Flying Instruments - Stack instruments the correct way so they disappear before the stack grows too tall. Match by family, instrument or sound. Similar to Tetris or LineUp (if you know those)
Music Mania - A quiz game about musical instruments.
Orchestra Game from The Magic Flute - Help fill the orchestra by matching the instrument to the sound. Then watch them all play together.
Arts Alive - Site with information about instruments, composers and even some games.
Making Music Fun - Lots of resources on musicians, instruments and general music.
The Piano Guys