These IMUSA Stackable mugs that's what! I saw these in a "youtube" video tutorial for the Keurig Brewer and just had to have them!
They're perfect for smaller kitchens and dorm room use too. It says that they're for Capuchino use but it's just the rize size for a smaller cup of coffee. If you drink smaller cups you can drink more of them, right?
IMUSA makes a bunch of different styles of colors of these guys and you can find them at retailers everywhere or online at: