This is a great design project because a) it incorporates recycling, b) it's a useful product, and c) the design addresses and corrects the flaws of earlier generations of the same product.
Shibuya-based Naruse-Inokama Architects, comprised of Jun Inokuma and Yuri Naruse, takes wood waste from houses and turns that into paper. The resultant paper is then formed into a stack of Post-It-like sticky notes that are in turn shaped like little houses. (They're called IE-TAGs as "ie" is Japanese for "house.") And as anyone who's ever seen a thick book loaded up with Post-It bookmarks can attest, the corners of the Post-Its get dog-eared like nobody's business. The resultant mess could hardly be called aesthetically pleasing.
The house shape of NIA's sticky notes, on the other hand, get rid of the corners altogether. I do wonder how they'll hold up if the book is, say, thrown into a crowded bookbag, and I'm curious enough to try 'em if someone would kindly start selling these at a store near me. (Muji, get on these!)