Sleeping in a bunk bed? If you have lots of baseball caps like I did, you can store your headgear by converting a wire hanger into a hat rack.
Instructables has a guide for twisting a wire hanger into a hook for your ball caps underneath the bottom of the bunk bed. The wire hanger holds the hat in place without taking up much space. If you're in the top bunk, you're out of luck. Check out the link for all the steps along with the pictures
Dorm Room Hat Rack [Instructables]