To fully control where a viewer's attention is drawn to on a photo, highlight the subject of the image. Some filters that create a vignetting effect help you achieve that purpose. However, such filters require the main subject to be in the center of the photo.
Radial filters in Adobe Camera Raw 8.0 enable you to direct attention to specific portions of the image to where you want the viewer to focus attention. For example, you can use the Radial Filter tool to draw an elliptical shape around the subject, and increase the exposure and clarity of the area within the shape to bring more attention to the subject. The subject can be off-center, or anywhere in the photography.