This storage shelf unit can be modified to make it longer or wider. It is perfect for behind the door in the bathroom or perhaps the childrens bedroom. Free building instructions available at the link.
Build this freestanding open shelf unit to keep things handy in the bathroom. Free plans at This Old House.
Build this small open shelf unit using either recycled lumber or new. Beautiful. Here are the free woodworking plans.
Here is a tutorial to build a shelf unit for the bathroom although it could easily be hung in any room. Free plans at Shanty2Chic.