Torafu Architects - "S-SHELF"and "SS-SHELF" are designed for use in small spaces, to store small things. In hallways, bathrooms and small terraces the slender form stands without interrupting the space.
I wrote a whole post about swapping your bookcases for wall-mounted shelving. Wall-mounted shelving takes up less space, and can almost appear to blend in with the wall. Image from Stadshem, via Freshhome.