My Butlers are crazy about their 'Peat Bog' hide- a lidded Kool-whip tub with a door in one side filled with wet sphagnum moss.You have to take care to keep it clean and fresh, but so far they seem to be benefitting greatly from the moisture- especially the smallest ones.
My snakes really like to play in sphagnum moss too. Sometimes I put a bowl of it in their enclosures and let them play in it for a few days...then I take it out because I get sick of dealing with it.