You can look at some of the colored ones, not sure how many are available. Appears to be Typhoon Bordeaux granite. Of the standard colors, almond or ivory would look best.

I had copper outlet and switch covers made by HouseJewelry.com. They work with all metals and can match samples.

Visit a good tile showroom, and check out Questech. They have outlet covers in stone looks as well as metal that could work for your space.

I actually found a stone one I liked online at Lowe's. I am taking a piece of granite with me to see if it will work and looking at some of the other suggestions as well.

Yeah, there's one at Lowes that's actually plastic but has a great color between gray and brown (they call it nickel) -- I've used it on backsplashes of both colors to great effect.

When we remodeled our kitchen, the electrician brought 4 or 5 samples of switch plates, in various shades of white/off white/cream. I chose the one that best matched my painted backsplash. Presumably there are just as many choices for darker colors - more than the white, almond and brown available at the big box store.

My Mom used to be a wallpaper hanger, and often put wallpaper behind clear covers, as palimpsest suggested.