Say you have a skin texture that is too dark. Here is an easy way to lighten it up in Poser 5. Just go to the material room, select the body sections you want to lighten, got to the texture map, and reduce the Texture Strength by an amount that gives you the shade you want. A value of 0.7 to 0.5 seems to work well. (Of course you can alway darken the texture by putting a color other than white in the diffuse color box)

Here are the material settings.

The texture strength trick works in poser 4/propack too, I have used it myself quite a few times before.

You can also lighten a texture by using a colour math node. Set it to Add, plug your texture into Value 1, and set Value 2 to some shade of grey.

Surely using a maths node makes the rendering time longer when just reducing the texture strength wont?

Quite possibly. Just presenting some alternatives, xantor.

While the Add node is a bit simple, other math nodes can do non-linear adjustments. You might not want the lighter colours any lighter, for instance.