Here are a few links to a few unique swithplate makers.

http://www.switchplatefactory.com/Natural-Stone_c_121.html?gclid=CPy49anHtakCFRphgwodsj35JQ

http://www.stonewallplates.com/travertine_switch_plates.html

http://www.graniteswitchplates.com/

Good luck.

Here is the link to the ones I bought. I found that Lowes carried this brand both in the store and online. It matched perfectly to our backsplash.

http://www.questech.com/cast_stone_sandgate_accessories.html

those looking for different colored switchplates look up Lutron renu also. I saw an ad on TV that they've come out with new options.

We had Columbia Gorge Stoneworks make switchplates for two of our bathrooms; we sent a travertine tile from our hall bathroom, and a White Thassos marble tile from our MB, marked where we wanted the plates cut (from the travertine), and they made the most beautiful switchplates for us. They were wonderful to deal with, too.

Here is a link that might be useful: Columbia Gorge Stoneworks