I love this topic! I use music all day long. I have all my kids' music in my ipod so I don't have to change CDs.
In the morning, my kids work at the tables as they arrive (in the beginning they are doing exploration with manipulatives, eventually it will be our journal time). I play music to signal them to clean up and join me at the carpet. I may play "Oh What a Beautiful Morning" from Chicken Soup for Little Souls or "The Goldfish" by Laurie Berkner (my favorite kids' music!).
Then we share our schedule for the day and write a morning message. Next it is time to get up and dance!
And practice our sign language alphabet to Carole King "A Alligators All Around"
Then I read a book, we have some math and when it is time to clean up for recess, I play another song! I use Jack Hartmann for math songs and one of our favorites is "Countdown to Blastoff."