The 12 Composers of Christmas

Here's what you should hear:

DAY 1: Bach's Invention No.1 in C Major. Hear here.

DAY 2: Mozart's "Là ci darem la mano",
Giovanni/Zerlina duet from Don Giovanni; the melody is sung by a baritone, but transposed up a third, so for now he sounds like a tenor. I'm going to try to fix that. [UPDATE: Fixed in Version 2.1] Hear here.
DAY 3: Brahms' Waltz No.15 in A-Flat, Op.39
It wasn't originally written for Giovanni and Zerlina to dance to, by why not? Hear here.
DAY 4: Vivaldi's "Spring," 1st mvt, from The Four Seasons. Hear here.

DAY 5: Beethoven's Symphony No. 5, 1st mvt. Hear here.

DAY 6: Schubert's accompaniment to the song, Erlkönig
We also hear a last desperate "Mein Vater, Mein Vater" on Day 12.(Yes, in the original the notes are marked as triplets, but they can just as easily be heard as sextuplets. Let's call them sextuplets.) Hear here.
DAY 7: Stravinsky's The Rite of Spring, "Dance of the Youths and Maidens"
These famous chords aren't really notated in 7/8, but the score feature many asymmetrical accents that give the impression of irregular meter. Hear here.
DAY 8: Tchaikovsky's Piano Concerto No. 1, famous octave passage from finale. Hear here.

DAY 9: Wagner's "Ride of the Valkyries" from Die Walküre
Yes, there are nine Valkyries, although Brünnhilde doesn't sing in this scene. Hear here.
DAY 10: Chopin's Etude in A-flat, Op. 25, No.1
Yes, Chopin really had only ten fingers; sometimes it seems more are needed. Hear here.
DAY 11: I made this one up, but Charles Ives certainly wrote more than one 11-note cluster in his life.
Some of his piano works call for the pianist to hit as many notes as possible with a block of wood! Hear some Ives here.
DAY 12: I also made this music up, although I did carefully construct a 12-tone row of which Schoenberg would be proud.
The row is in the R.H., with its retrograde in a series of three-note chords in the L.H. I'm sure you noticed that.