SEC chick, Mrs. AdL, and Mrs. SD, take note and buy this mobile:
http://www.geniusbabies.com/newtinlovsym.html
Today I heard my kid's first full-blown squeal of delight. She absolutely loves this thing.
I don't know how much validity there is to the classical music theory, but it beats the heck out of twinkle twinkle little star, and the motion and shapes colors of this mobile fascinate the baby.
Don't waste your cash on any twinkle twinkle pastel bullshit.
The only downside to this thing is that I can't attach it to my bed, but at least I feel better about having spent money on a crib that would otherwise go unused.