A Puerto Rican coworker turned me onto hot chocolate with cheese in it. I believe the traditional method is basically just to put some cheese in the cup and you end up with a melted glob of cheese to eat with a spoon as/after you drink it. I've played around with that as well as actually incorporating the cheese into the drink itself, melting it all together on the stove.
Kind of gets you some of that well-tested sweet/salty/savory combo. I dig it in a Mexican hot chocolate with some cinnamon and chili powder.
I believe the traditional cheese is edam, I've tried that as well as cheddar and a few other cheeses, they all seemed to work pretty well, try it at your own risk if you go for anything too funky