These apps are incredibly fun and helpful for anyone learning music.
Joytunes Music Education Software
Piano Dust Buster 2 for iPhone and iPad
Synthesia Piano Game - for all systems, requires MIDI keyboard with USB adapter
Casio PX350 - This keyboard is excellent for the price.
KDFC - Listen online or on the radio. If you have this station playing for your child everyday, they will receive and excellent musical education and appreciation.