A few days ago, I wrote a barbershop tag for my girlfriend Chelsea.
My multitrack of the tag (sung a half step lower than written):
My goal was to write a “bloom” type tag where all voices start on a single unison note, and travel in smooth contrary motion to the final chord. Some great examples of this kind of tag are Cry and Sleepy Time. I took this idea so its logical extreme by using almost entirely chromatic contrary motion. In fact, of the melodic intervals in the tag, 19 are half steps, 9 are whole steps and 2 are perfect fourths.
The sheet music: beside_my_side.pdf
I made a little video that teaches you all the parts by ear: