Here, I changed the blend mode of the filtered layer to Multiply.
In this case, I put the blend mode back to Normal and noticed that the filter introduced a slight hot spot on her face, so I added a layer mask (by clicking on the Add Layer Mask icon at the bottom of the Layers palette) and used the Brush tool (B) to paint on it with black to hide that area of the filtered photo, eliminating the hot spot.
Here, the filtered layer was duplicated and its blend mode changed to Multiply, with the opacity lowered to 60%.
In this example, I added a Hue/Saturation adjustment layer, turned on the Colorize checkbox at the bottom right of the dialog, and experimented with the Hue slider.
Of course, this doesn't only work with portraits! Here's a before and after of another photo where I used this same Flashlight lighting effect (and used a layer mask to lessen the effects of the filter in the edges of the flower)
Before adding the spotlight effect
After adding the spotlight effect