[Doug Nelson]

A trick that can be borrowed from traditional photography to add an almost subliminal enhancement to many pictures is "Edge burn".

Edge burn is simply darkening the edges of the image. This is to be done very subtly. If it's recognizable, you've done too much. It should be a "they don't know why, but it's interesting" type of thing.

Edge burn draws in the eye and provides a more comfortable sense of "wholeness" to an image.

At it's most basic you can simply draw a selection rounded rectangle on a blank layer, invert, feather, fill with a radial gradient from the center out, then use multiply blend mode and lower the opacity.

But ideally you'd do a custom mask, shaping it to the composition.

Some things to keep in mind:

Always use a separate layer
Be careful with whites on your edge. No real point in burning whites, they just look dirty.
Be so subtle you can hardly notice it yourself, then be a little more subtle.
Check it on your final intended output. Prints will require very different settings than screen.
This is done after everything else, especially sharpening.
This is art, not science. There's no formula for the "best" edge burn.
Remember you're talking to the subconcious, aiming it at what you want it to see. Don't go for "hey dude, good edge burn".
There are many other ways to do this. Try any you can imagine. What works for you will be yours, someone else will have a different technique that works best for them.

I bring this up because it's applicable to restoration and retouching, not just "art" photos.

And remember, always, subtle, subtle, subtle.

[DJ Dubovsky]

This sounds familiar. I think I may have heard of it before but I'm not sure where. Sounds like a good tip. I'll have to give it a try.
DJ