The Fox Theatre's organ, otherwise known as Mighty Mo, reverberates throughout the theater Tues., DEC. 18, for the holiday sing-along LARRY, CAROLS AND MO with the Atlanta Boy Choir and the Ebenezer Baptist Church Choir. A screening of the Christmas classic Miracle on 34th Street follows, after which the music continues with organist Larry Douglas Embury and the Atlanta Gay Men's Chorus. It's fair to say that with all the holiday cheer, the audience will leave wanting mo'. Free. 6 p.m. 660 Peachtree St. 404-881-2100. www.foxtheatre.org.