One imaginative user over at Instructables, SHIFT!, got the idea to build a personal AC unit in a travel coffee mug. It's similar in idea to another DIY AC unit made from a cooler, except much, much smaller.
Shift used a handheld fan, some copper and plastic tubing, a water pump from a desktop zen garden and a battery pack for his air conditioner. He bent the copper tubing in a coil around the back of the fan, connected that to the plastic tubing which goes down through the cap into the mug and connects to the water pump. The water pump and fan are powered by the battery pack which is attached to the outside of the mug. From there he just added ice water, which pumps through the copper tubing, which cools the air around the fan. Neat! [Instructables]