Here'sa very simple way to focus a viewer's attention on a particular part of your image. Layer Masks are quite handy things for this sort of effect.

To get started, open the image you want to mask and duplicate the Background layer by dragging it into the "New Layer" icon at the bottom of the Layers palette (or simply press +). Now, double-click the original background layer to make it editable and accept the default new name offered ("Layer 0"). Edit this layer a bit to make it less obtrusive by blurring it, desaturating it, running a brush stroke filter on it, or any/all of the above.

I just used a Motion Blur filter on it, and desaturated it with a Hue/Saturation Adjustment layer:

Now, single-click the new background copy layer you created to select it, and make your regular image corrections (such as Levels, color balance adjustments, sharpen, etc. - you want to get this layer looking as good as possible, since it will be the layer that's mostly visible when we're done.).

Create a mask for this layer by clicking the "Create Layer Mask" icon at the bottom of the Layers palette while holding the button. Your mask will be created already filled with black.

Select a "grunge" or dry media-type brush from the brushes palette, and begin painting with white to reveal the edited top image - your "background copy" layer. With masks, remember that black hides and white reveals underlying layers.

Don't forget that you can also run filters on masks; for this example, I used a dry media brush to reveal the image, then blurred the mask with the Motion Blur filter, then ran the Wind (Filters>Stylize>Wind) filter a few times in both directions.

This is how my image turned out:

For a different effect, create a new layer above the original background layer - now named "Layer 0" - and fill it with the color of your choice. Your mask will reveal this layer instead of the blurred original:

This is a nice effect for printed materials or a splash image at the top of a webpage.