My little guy loves all kinds of music, but here are some of his favorites:
Suzuki violin CD - we can't start him on lessons here until he turns 3 in another half year, but he sure does listen to the CD a great deal. I have all the songs memorized!!
Geography songs -
http://www.singnlearn.org/khxc/index.php?app=ccp0&ns=prodshow&ref=136 I really love these songs. When he was an infant, I learned the songs so that I could rock him to sleep with geography songs...I used to sing about the islands in Oceania and he'd go right to sleep. (by the way, I highly recommend Sing n Learn. I love their online store!!).
Spanish Songs - We have a CD of traditional Spanish songs, and it's really cute and upbeat. We listen to this one a great deal, especially when Maria (our Spanish nanny) comes.
Baby's First Words in Chinese -
http://www.amazon.com/Babys-First-Chinese-Living-Language/dp/1400023645 The songs on this CD are really varied, but when our foreign exchange student from China came he was able to sing them all. He said the pronunciation is perfect.
Plus, of course, classical. We have hundreds of different classical CD's that we put in whenever we want. My son really likes piano pieces.