I ran across a blog that has an embedded MP3 player in it (http://wavingwords.blogspot.com) with the incredible voice of Lhasa de Sela (a chamada "Edith Piaf" of Mexico).
Click on the link above to listen to 2 or 3 of her songs -- the quality is much better than the two YouTube videos listed below. BLOGGER'S NOTE OF DEC. 16, 2007: unfortunately the blogger deleted the MP3 player.
Lhasa de Sela singing "De cara a la pared"
Lhasa de Sela singing "El desierto":