The girls' music teacher told us about the "Amazing Slow Downer". It slows down the music you're listening to (Suzuki violin book 3, in our case) so the musician-in-training can actually hear what every single note is supposed to sound like!
Wowee wow wow. (Totally rockin').
Here's the one I used... http://download.cnet.com/Amazing-Slow-Downer-for-Windows/3000-2139_4-10076514.html
Free only in trial version (natch), it's pretty pricey to meet at $49.99. But then again if it helps the girls with their music..... might be worth it.
Oh, please forgive my use of the delicious adjective "wicked" in the title of this post. I've been informed by my 10 year old that moms are not allowed to say that. (whatev)