Wide angle lenses are very usefull in landscape photography where you may wish to capture a very wide expansive landscape. The image above of Coolangatta was taken with a 14mm wide angle lens on a Nikon DX camera. A 14 mm lens on a DX type camera may not seem all that wide, on this type of camera due to the crop factor lenses of up to 10mm may be found to be very usefull. On a full frame 24x36mm type camera a 14mm lens is considered to be very wide.
When using wide angle and ultra wide angle lenses it is good to include some object close in to the foreground, like in the above image to give a feeling of depth in the image.