Is it possible to refinish some newer Ws6 rims? The non-chrome kind..

I was thinking about powder coating a set black, if it's possible..

 

Sure it's possible. They just need to blast the old finish off and then powder coat them whatever color you want. Probably cost you a couple hundred bucks most of that in the labor of preparing the wheels for coating.

 

Make sure if you go black that you keep a silver lip around it, otherwise it won't look that good. Actually, keep a silver lip with any color that you go with.
I like the silver that I have,

 

I was thinking about coating the whole thing black..I've seen some Ferrarri's like that and it looks sweet

 

Only problem with the entire wheel being black is that you can't tell where the wheel ends and the tire starts.
If you have 18" with really low profile tires and thin spokes so that you can see the rotors, then you can get away with it.
Otherwise I think it might look ugly.