It's a mug, a bowl, and a water storage container! Backpacking gear doesn't have to be expensive to be good. Ziploc's Twist'n Loc containers are a great multi-use backpacking item.
After wandering the aisles at my local outfitter for a half hour, I walked out with just a pair of socks. Everything else I was looking for was just too heavy for my backpacking style. Afterwards, I ended up finding this 3-pack of Ziploc containers at the grocery store for just $3 US. The size small weighs 1.4oz, which makes it half the price and 0.4oz lighter than the pictured REI plastic mug. When you consider that the Ziploc container has a larger capacity (2 cups vs 1 1/2), and a lid, it seems like a no brainer.
Since the lid has a water tight seal, you can also use it to carry extra water. There is a 1 cup marking on the side, which can be helpful for preparing meals. For enjoying a hot bowl of soup or a mug of hot coffee, you could make a simple cozzie for it, but I just put on my glove liners to insulate my hands from the heat.
A versatile, UltraLight, UltraCheap Backpacking solution...perfect! Replace one of your water containers with this and it won't even add any weight to your pack!