I thought about trying to take digital pictures of the wallpaper, but it really wouldn't come out very well. I finally decided just to describe them, since you can of course see them for yourself on your computer if something is actually available for you to buy.

Common Wall
This is what I started out with. It's actually not bad - it looks quiet and medieval. It's a beige base wall with wood beams criss-crossing it. There are also a few bricks showing through. It's the quiet cottage look.
Cost: 1,240 bells

Concrete Wall
I suppose this is fine if you're going for the post-industrial look. Bleak and boring. It looks like grids of grey with 6 dots on each rectangle.
Cost: 800 bells

Ivy Wall
I like this wall a lot, it's what's in my own home. It is red brick with green ivy climbing up it.
Cost: 1,250 bells

Plaster Wall
A basic plaster wall
Cost: 220 bells

Regal Wall
This is a vertical striped wallpaper. The base stripes are gold with little dark crowns on them, and dark wood beams (vertical) every few stripes.
Cost: 2,240 bells

Animal Crossing Wild World Walkthrough