Hey,

I am someone with dark brown hair, thick black eyebrows and dark brown eyes. I have a quite dark complexion, but my skin (especially the parts that never see any sun) is too pale, I believe, to match my hair colour and the like. It could look good on a blonde or red haired person, but doesn't suit me.

In the summer it'd be all right, but in the winter I sometimes look ghostly due to the contrast. Is there any way to prompt the skin to produce more pigmentation? I know there are skin lightening products, but is there also something that darkens the skin permanently?

There's no way to make pale skin permanently darker. There are temporary measures, such as sun exposure or sunless tanning products that will darken the skin. We all need some sun exposure, but too much sun can be dangerous. I recommend using a self tanner or bronzer if you want a darker skin tone.