I think we can all agree that the photo below is a pretty common, albeit horrible den. Well, Southern Living featured the makeover of this den into a living room/craft area over the holidays. I think it turned out great, and is a great example of efficiently using the space you have.
The before....
The after! (Click on the image for a larger view.) Notice the narrow bookshelves on either side of the fireplace which offer storage that didn't even exist before - a perfect example of making the most of your space. A couch instead of chairs offers more seating and cozies up the room. Large baskets under the console at the back of the chair create storage, and the table acts as a desk when needed. Shelves on the wall create a pretty gallery space.
A pretty wreath hung from the bookshelves.
A corkboard displays invites and cards.
What do you think of this makeover?
via Southern Living