This tutorial was meant for Adobe Photoshop CS+ (you can also use 7.0, but CS+ is better).
1. Take out the image you want to add an amazing color affect to.
Here's the one I'll be using:
2. Add a color balance layer, with a bit of random color to it (I'm making mine
an odd shade of blue). Once you're done that, make your image black and white
[ an easy way of doing this, is Ctrl+U, "Colorize", then put the saturation all the way to the left. ]. This way, the color balance layer completely colors the image.
3. Here's where the fun begins. Grab a large soft brush (300 soft is what I'm using).
Soft brushes are the ones that have soft edges, like this one:

Make a new layer that's below the color balance layer, but above the image.
Set the blending mode to "Linear Light". And brush on the spot you want to add the effect to. For this, I'm doing it on samus' gun. The brush color must be in a color that does not coressponde to the color balance layer at all! IE: if the color balance layer is blue, make the brush red! Do 1 click on the spot with the brush, then switch to white and brush it in the exact same spot. Now, do It again but with a different color, on the same layer in the same spot. You can maybe even click twice if you wanted to. IE: Instead of red now, maybe do it with purple.
This is what I got:
