Yaks have been commercially valued for years because of their milk, meat, wool, and dung. While I can honestly say that I've never enjoyed a tall glass of yak milk, I do own several awesome 100% yak wool sweaters and three pairs of yak pants make my butt look like a fully-armed furry neutron bomb. I've also heard that a yak sandwich is actually quite delicious but most restaurants don't offer it because it sounds too much like a puke sandwich.