Hey everyone.
Today we'll be going from
this
to this 
Made with: Photoshop CS2 (translatable, at least for GIMP)
Difficulty: Medium
PSD: Yes, get it here
1) Take your image and apply the adjustments needed (cropping, sharpening etc etc.), I suggest you use images which are moderately bright; this tut won’t really work with really dark or really bright ones.
2) Duplicate your image twice, set the first layer to screen with 50% opacity.
Set the second layer to Soft Light 75% opacity.
3) It’s time to fill a new layer with color (Layer>New Fill Layer>Solid Color).
I normally would use a very dark purple, preferably #140736.
Images which have plenty of ‘cold’ colors may need a warmer shade instead of purple, so try something like #170000 which is a very dark shade of red.
Afterwards, set this layer to exclusion.
4) Duplicate your base image and drag it to the top, set it to Luminosity with 80% opacity
5) Duplicate that layer and leave it as it is.
6) Now, go to Layer>New Layer Adjustments>Levels and fiddle with the settings, mine were;
15, 1.28, 245.
7) Paste this texture by
brokendogma and set it to screen, fiddle with the opacity, and make it look like there is a light source coming from the corner – by doing this, rotate it to wherever the person in your stock’s face is looking. On mine, they are both facing the bottom left, so I just left the texture as it was, if they were facing the opposite direction, I’d rotate the texture horizontally to the right. All in all, you get what I mean.
If you are using my base, I set the opacity at 20%
8) This step is pretty much optional; I wanted Kristen’s face to be lit up a bit more too, so I duplicated the layer where the texture was and set it Soft Light at 20-21% opacity.
Note: On other images I feel like the light source hasn’t spread onto the stock enough, so what I do is take a soft brush and I start smudging the texture, making the light spread across the torso/neck/face etc.
9) This step is also optional up to this point; you can add some curves if you want;
Settings are:
Input: 79
Output: 71
When we are finished you can decide whether to take them away or add them back, I’m pretty undecided myself.
10) It’s time to add some selective coloring;
Apply these settings:
Reds:
-29, +7, 0, +14
Magentas:
+33, -22, +20, +100
Neutrals:
+6, -1, -6, +4
Note: For GIMP users, you can use color balance (I’m not sure if PSP users have this or not, sorry);
Settings are;
-14, -14, -14.
To be honest, the result is not 100% the same, but the colors are really similar.
11) You might want to brighten and contrast your image now, settings are;
+8, +8
I also duplicated the layer, but you can choose to not do it.
12) Paste this texture, still by brokendogma and set it screen, I set the opacity at 61%
I suggest rotating it to the opposite direction from where your stock is facing, and also erasing some parts that cover the face etc., but be creative, move it around and see what fits best.
13) You might want to contrast your image a bit more; I put my settings at;
-9, +3
This step is optional, it really depends on your image and what you want to do with it.
14) Duplicate your base image and drag it to the top, set it to Soft Light with 50% opacity.
15) At this point, my images seem a bit too red, so go on Hue/Saturation, and apply the following settings;
+4, -2, +2
16) Time for Curves again, you can choose not to add them though;
Input: 77
Output: 82
17) Final step, duplicate your base image and drag it to the top, set it to Hue (My image went a bit yellow at some point), with 25% opacity, and you’re done!
I added some tiny text just to finish it off.
Other examples:

Hope you guys like it :) I'd love to see what you've come up with.
Tell me if there are any mistakes and I'll quickly fix them.
this
to this 
Made with: Photoshop CS2 (translatable, at least for GIMP)
Difficulty: Medium
PSD: Yes, get it here
2) Duplicate your image twice, set the first layer to screen with 50% opacity.
Set the second layer to Soft Light 75% opacity.
3) It’s time to fill a new layer with color (Layer>New Fill Layer>Solid Color).
I normally would use a very dark purple, preferably #140736.
Images which have plenty of ‘cold’ colors may need a warmer shade instead of purple, so try something like #170000 which is a very dark shade of red.
Afterwards, set this layer to exclusion.
4) Duplicate your base image and drag it to the top, set it to Luminosity with 80% opacity
5) Duplicate that layer and leave it as it is.
6) Now, go to Layer>New Layer Adjustments>Levels and fiddle with the settings, mine were;
15, 1.28, 245.
7) Paste this texture by
brokendogma and set it to screen, fiddle with the opacity, and make it look like there is a light source coming from the corner – by doing this, rotate it to wherever the person in your stock’s face is looking. On mine, they are both facing the bottom left, so I just left the texture as it was, if they were facing the opposite direction, I’d rotate the texture horizontally to the right. All in all, you get what I mean.If you are using my base, I set the opacity at 20%
8) This step is pretty much optional; I wanted Kristen’s face to be lit up a bit more too, so I duplicated the layer where the texture was and set it Soft Light at 20-21% opacity.
Note: On other images I feel like the light source hasn’t spread onto the stock enough, so what I do is take a soft brush and I start smudging the texture, making the light spread across the torso/neck/face etc.
9) This step is also optional up to this point; you can add some curves if you want;
Settings are:
Input: 79
Output: 71
When we are finished you can decide whether to take them away or add them back, I’m pretty undecided myself.
10) It’s time to add some selective coloring;
Apply these settings:
Reds:
-29, +7, 0, +14
Magentas:
+33, -22, +20, +100
Neutrals:
+6, -1, -6, +4
Note: For GIMP users, you can use color balance (I’m not sure if PSP users have this or not, sorry);
Settings are;
-14, -14, -14.
To be honest, the result is not 100% the same, but the colors are really similar.
11) You might want to brighten and contrast your image now, settings are;
+8, +8
I also duplicated the layer, but you can choose to not do it.
12) Paste this texture, still by brokendogma and set it screen, I set the opacity at 61%
I suggest rotating it to the opposite direction from where your stock is facing, and also erasing some parts that cover the face etc., but be creative, move it around and see what fits best.
13) You might want to contrast your image a bit more; I put my settings at;
-9, +3
This step is optional, it really depends on your image and what you want to do with it.
14) Duplicate your base image and drag it to the top, set it to Soft Light with 50% opacity.
15) At this point, my images seem a bit too red, so go on Hue/Saturation, and apply the following settings;
+4, -2, +2
16) Time for Curves again, you can choose not to add them though;
Input: 77
Output: 82
17) Final step, duplicate your base image and drag it to the top, set it to Hue (My image went a bit yellow at some point), with 25% opacity, and you’re done!
I added some tiny text just to finish it off.
Other examples:

Hope you guys like it :) I'd love to see what you've come up with.
Tell me if there are any mistakes and I'll quickly fix them.