I have the Andrea Bocelli and Sarah Brightman duet...
and I've seen Bocelli in concert...
and I have Sarah Brightman's entire album...
along with that Bee Gees dude and Barbara Striesand's album (my wife forced me).

Others include:

Adam Sandler's "At A Medium Pace"
Dalida
Lords of Acid's "Pussy"
Bloodhound Gang can get pretty perverse with songs like "You're Pretty When I'm Drunk" and "I Wish I Was Queer So I Can Get Chicks".