I'm already a big fan of these little rolls of Japanese masking tape. In addition to playing a role in some of our wedding paper collateral, they make gift wrapping a breeze (and cute) and make literally taping pictures or notes to the wall a viable option outside of a dorm room.
But now there's this - and I need it. Giant rolls of washi for your walls. You can layer them, you can make stripes or plaids or whatever else you can imagine. Slap it on the wall and peel it off and throw it away when you're done. Amazing.
Unfortunately this partnership between Japanese furniture and wallpaper purveyors Sincol and washi tape/stationary co. MT is only available in Japan. A buying trip might be in order.