The Shadow/Highlight tool should help. If you don't like the results of that, one of the things I like to do is to create a monochrome mask of the image using a median filter (or whatever method you prefer to blur out the small details while keeping the larger areas) and add it as a color dodged layer with a curves adjustment layer to invert the image and control the effect. Color dodging with an inverted image is a divide, so the darkest areas of the image will have the most boost. Because dividing by zero is infinity, if you don't raise the black level ( or rather dim the bright areas of the inverted image) you will get something pretty ugly.
I used that technique on the faded photograph in
bring back the color thread to try to pull out the girls eyes a bit. If you
look at the action I recorded for the Nilda image and uncheck the "levels" and "flatten" steps you'll get something that sort of works. When I run it on the JPEG you posted here, I prefer a mask that is pastel instead of monochrome (replace the channel mixer step with negative saturation) just to counter some of the ruddiness the boost adds. I'm not sure if that's because the image is a JPEG. You might want to experiment a little with the original.
-Colleen
