Those "hanging shelves" that go over doors or in wardrobes are really handy for nappy storage. I have fabric ones that fit 20 nappies perfectly, could really do with another one. Even the likes of a DVD storage unit with all the little shelves is compact and fits nappies in well! They also show off the nappies, rather tha having them shoved in a basket.
I must admint though that mine rarely get put away in the little shelves, they stay on the clotheshorse until they're used or dumped on the floor to make room for the next load to dry