.
It seems every year we go through this.
The shopping centers and radio stations play Joy to the World and Chestnuts Roasting on an Open Fire and Frosty the Snowman and White Christmas over and over and over. They're trying to induce a shopping spree!
It's Not Christmas Yet!!
What about:
Veni, Veni, Emmanuel
Hark! A Mystic Voice is Sounding (En Clara Vox)
Behold! Behold, He Cometh!
Creator Alme Siderum
En Clara Vox Redarguit
O Come! Divine Messaiah
Immaculate Mary (Her Feast Day, today, always falls in Advent)
Rorate Coeli
See He Comes
Like the Dawning of the Morning Fr. F.W. Faber
Magnificat (words of Our Lady from before the Nativity)
Veni, O Sapientia
The many hymns to Our Lady are often suitable for Advent, as well:
Hail! Star of Ocean
Alma Redemptoris Mater (Advent through Purification inclusive)
Ave Maris Stella (Edvard Grieg setting is very nice for Advent)
Salve Regina Coelitum
Tota Pulchra Es, Maria
Sub tuum Praesidium
Ave Regina Coelorum
Ave Maria! O Maiden, O Mother
O Purest of Creatures (Immaculate Conception)
Whither thus, in holy rapture? (the Visitation)
Hear Thy Children, Gentlest Mother (M. Haydn)
O Sanctissima
Other hymns with an Advent theme
Jesus, Jesus, Come to Me
Dear Angel Ever at My Side
Veni, Jesu, amor mi
The Angel Gabriel ("..from heaven came, his wings as drifted snow his eyes as flame")