Strangest, maybe not, but best backed bow I ever saw was made by the bowyer that taught me, Barry Meyer. He sinew backed an osage bow (oh, how daring), but then backed the bow with a single skin from a gaboon viper. 'Boons are one of the top 5 deadliest snakes in the world and not easy to come by. He happened to have a contact at Reptile Gardens that saved the nasty critter for him.
Their latin name kinda fits....Bitis gabonica.