Nothing calms children down, and turns their mood positive like singing to them (whatever the quality / pitch of your voice).

I've introduced my kids (twins (M+F) age 6yrs) to Harry Belafonte (think Look-A-Boo-Boo), Teresa Doyle (Canadian - can't recommend her highly enough), World music for children, Wagner (via the wonder of the Ring story - dragons, knights, trolls, etc, and Patrice Chereau's video), Mozart's Magic Flute (Bergman's movie with the children's perspective of the opera), soundtrack to Hans Christian Anderson (Danny Kaye singing), Cole Porter, Rogers, Hart and Hammerstein, Dorothy Field lyrics, etc. Almost anything with young children singing will get their attention.

What I avoid like the plague is infantalizing "children's music" that has no intrinsic musical depth (think almost any preschool TV program, with the possible exception of some sesame street pieces).

I think the common theme is identifiable story, rhythm, recognizable lyrics (maybe not the Wagner), and at least one parent enthusiastic about it. Young children need to identify the music with someone special (how else could I explain my daughter's attachment to Hanna Montana music!!!).

So if you're enthusiastic about it, sing (or dance) along with it, and support their enthusiasm to sing, hum, beat the pots and pans, they might not share your musical tastes, but they'll have enough confidence to form their own later in life.

My son was born at home. He arrived with a breathing problem, they call it "panting and flaring." All signs were fine, he just couldn't stop panting. After consulting a doctor by phone and pursuing various things, there was no improvement and my son was placed on oxygen. FInally, the midwife handed the baby to me and said "do something." I lay on the floor with the child on my chest and sang octaves and perfect fifths in a low baritone register. Within twenty minutes, my son had calmed down and was breathing normally without the need of oxygen. I had recently seen a group of Tibetan monks chanting at Carnegie Hall, and recalled the calming efect of it.

I had two posters above my crib as a youngster in the '80s: Sun Ra and Boy George. Oddly, the musician that I have become is pretty much a combination of those two guys.

My Dad loves to tell the story about how on the day I was brought home from the hospital he blasted Beethoven on the stereo. In 1977, his purpose was not to introduce my young mind to Classical music, but to teach me to sleep through loud sounds.

I'm not sure if this act helped me appreciate music - I did spend much of my youth in ballet classes by my own choice - but I can say that I have no problem sleeping though loud sounds!

I would play Brian Eno's "Discreet Music"

I am an opera singer, mostly having a career in new music, and it became very clear that my son's auditory experience in utero far preceded whatever I played for him when he first came home from the hospital. I practiced every day - and performed - during my pregnancy. Three weeks after giving birth I started practicing again, having propped him up in a "bouncy" chair, and started in on a lip trill warm up. It sounds like an extended brrrrr on pitch. His instant look of recognition and agitation made it completely clear that he had heard me practicing while he was still a fetus. His eclectic musical taste now has to be a product of his lifelong exposure before and after birth to all the musical genres to be heard in our home.

Will playing Mahler make your kid neurotic?

My Little boy has been going to music "classes" since about 6 months of age - he loves them and seems to really respond to music - he even sings along. It is a real joy to me to see his expressiveness emerge in reaction to musical sound.

We don't try to cultivate an appreciation particularly for classical. We are not of the belief that it is superior to popular music. As in Bach vs Radiohead - I don't see the difference.