I recently stumbled upon this interesting teaching tool: a foldable, pocket whiteboard.
It peaked my interest because there were several times over the past year when I was out teaching and wished I had a writing surface to get a complex concept across to my students. Beach sand and a stick can only go so far when explaining the wonders of a developing cold front.
The whiteboard is made up of 27 mini pieces that folds up to roughly 3”x5”x0.2”. It folds out to 15”x27” giving you lots of whitespace to work with. The kit comes with a dry erase market and a microfiber bag which doubles as an eraser.
More info: thinkgeek.com