I would have posted this earlier, but the circumstances explained in the previous post prevented it.
At the Requiem Mass I celebrated at the CMAA Colloquium, the chant scholae also sang the traditional sequence for the Requiem Mass, the Dies Irae:
(Recording by Carl Dierschow, edited and optimized by me)
Solvet sæclum in favilla
Teste David cum Sibylla!
"Day of wrath, O that day,
which will dissolve the world in ashes,
as David and the Sibyll gave witness!"
(Go here for a complete text and translation)
Interestingly, though this sequence is not included in the Mass for the Dead in the modern Roman rite (Mass of Paul VI), it has never been suppressed, and exists as a "supplemental" text in the modern Breviary. Where it may be sung in the modern rite is a subject of some debate. At the Colloquium, it was sung, in keeping with Tradition, as a Sequence.
I am always moved on singing or hearing this, as it is a chant of great power and profundity, evoking the Last Things and our hope in Christ's mercy.