Ive heard that its the raw eggs that help your hair, anything high in protien like that i expect would work the same. and the oil in it would make it soft – ive never used it but i can see it working. the smell would put me off using it though.
if you want a good hair mask; now and then i put babyoil in my hair overnight, plait it so that it doesnt get everywhere then give it a real good wash out in the morning it makes it lovely and soft.
my housemate is cheap and uses olive oil but again – who wants to smell like a sandwich?