A couple of months ago, my husband came across the app ABC Music by Peapod Labs. He thought it would be great for my classroom, and I think he's right.
I hadn't had a chance to really look at the app until he was playing with our 7 month old niece a couple of weeks ago. She was delighted by all of the instrument sounds and video.
The App is basically an alphabetical list of instruments. When you click an instrument, it opens up a screen with a picture of the instrument and it's name. Along with each instrument are videos of the instruments being played. The app can be played in either English or Spanish; this is great for bilingual programs. It's available in the App Store for $2.99.
I plan to use this app with my Kindergartners this year. We will do a letter each rotation, hitting my benchmarks and supporting their classroom benchmarks as well. This will be a great way to end each lesson.