Not so much song, but just melodies. I wouldn't consider My Favorite Things a great song but that melody is amazing.

The Minstrel Boy, which is an old Irish song set to the melody of The Moreen. (Also like the melody to Danny Boy, while were on the subject of Irish tunes.)

Whistle Stop... there's so many Disney songs with great melodies.

You're f*$%ing telling me....

Every day I have to listen to the Disney Princess CD driving my daughters to school. Every day I get a new one of them stuck in my head for the rest of the day.