Danbo is a short word for "danboru", the Japanese word for corrugated cardboard. Its getting popular on Flickr and photo blogs. I am sorry but I do not know how to write the word in Japanese writing system.
Danbo, the robot out of cardboard boxes that is now popular subject of digital photography, is a character from a comedy manga series by Kiyohiko Azuma entitled Yotsuba&!, read as "Yotsuba to" which means "Yotsuba and".