Babies love music. When I was still pregnant with my son, I would place headphone on my belly and play all sorts of music for him. He heard folk music, drum beats, modern pop and rock, some classic rock and loads of classical music (particularly Holtz' the Planets Suite).
After Aiden was born, the music didn't stop there. I have a 4 CD set of lullabies that he got to listen to, and sometimes I would make up little songs and sing them to him. His particular favorite was my "Ivory Baby" song. I loved to hear him giggle and smile at me when I sang to him.
Sing lots of songs for your children, or if you choose not to sing, play them a variety of music on the radio or from your personal CD collection. Try using Pagan chants for lullabies. And when listening to music with your child, try dancing with them. Move with them, get their juices flowing if you will.