This setting of Psalm 51 by Cyprian Consiglio is a no-brainer for Lent. The verses are somewhat delicate and probably are better for a cantor, but that is a lot of cantoring and little singing for the assembly. I suppose it could also be used as a chant for private prayer during Lent.
The music of the last line of the verses has a odd sense of Fiddler on Roof about it.
The text is at spiritandsong where the sheet music can be purchased for download and you can hear a snippet of the song. They also give the alternative refrain, “Be Merciful, O Lord.” You can hear a duet version here.