One of the most creative ways to use a tall bookcase, is to modify it to swing like a door. Essentially you create hidden storage behind the bookcase. You can do this in a main living area, a bedroom or even a closet. Secret passages are fun for kids and adults alike, and a great place to keep items, or to even hide a desk area
Not quite what i had in mind, but puts a new perspective on the idea if i ever acquire a real house...think up the attic stairs hidden behind the more used books i don't mind sharing...and the whole attic could be my book nook/library!