Recently Nintendo released a firmware update that allowed for owners to buy custom home themes for their 3DS. I myself bought the Link Between Worlds theme for my own 3DS the moment these themes rolled out.
However, we in North America are only privy to a handful of themes so far, while Japan has many, many more. Those themes, most of them at least, will be making their way to the west eventually so until then look at this playlist from Nintendo Japan. This playlist will give you a quick video preview of all the Japanese home themes, including design and sound effects.
This Animal Crossing one is my most anticipated, just for that adorable Isabelle.