The UU hymnal "Singing The Living Tradition" has both "Be Thou My Vision" and another song "Wake, Now, My Senses" to the "Slane" tune.  It also has 3 English verses to "De Colores" (which I posted in a "De Colores" thread) and a lovely song based on I Corinthians: 13 called "Though I May Speak" which is sung to "The Water Is Wide" (which is the same lyric Mary cited as "The Gift of Love").  Then there is "The Flower Carol" to the tune "Good Kind Wenceslas."

Masato, as usual, you are wonderful.  Thanks for the link to the Vaughan Williams essay.

Nigel, I love your "Slaine" lyrics!!

Don't forget that "Amazing Grace" can -- and has been (effectively, I'd add) -- sung to the tune of the Animals' version of "House Of The Rising Sun."

Katherine Lee Bates's "America The Beautiful" was, for two years after it was written, sung to just about any popular or folk tune it would fit -- most notably, "Auld Lang Syne."

Mary in Kentucky, isn't the tune for "Glorious Things Of Thee Are Spoken" also the tune to "Deutschland, Deutschland Über Alles?"