The photo in this blog post is an example of negative space. The model, the awesome Twyla D'Vine, is off to the far right of the photo (or is that the far left). She is standing next to a very large pillar. Normally the rule of thirds would say to move her more toward the center so she and the pillar are in the right third of the shot. But I purposely put Twyla farther over to the side. The rest of the photo is pretty much empty. There is a slight pattern to the wall. But the pattern and colors are very sparse. So your eye is immediately drawn to the side of the image where the story actually is.
When you use negative space in an image it is really important that the "empty" area is pretty blank. You can use a stucco wall, or an adobe wall. In this case the wall is paneled, but the pattern is very simple. If the background is at all busy then you lose the effect because there is so much the eye can look at. So now the viewer needs to struggle to figure out what the photo is supposed to be about.
One other thing I did in this image was to have the model looking off camera instead into the image. This helps continue the tension for the viewer to look to the side, and ultimately off the image. It makes you wonder what is out there that we cannot see.
An image like this can also be used well in an advertisement, or in a double truck or two page full layout in a magazine or book. For an ad you could put text in the negative space. If your graphics designer is really good they will use the lines and composition of the existing image in designing how other elements will go in. If you put it in a magazine or book then the spine will run down in the negative area and not on the model or other significant element of the image. Sometimes when composing an image you need to pay special attention to the ultimate use of the image and let that guide your composition decisions.