back from the dead......
There are several plating processes that will yield a glossy smooth black surface. Some wear, some don't...I've got some black nickel and black chrome before though not many shops do that now due to the toxic byproducts. Black zinc plating is much easier to get and should hold up ok so long as your initial polish and post plate polish is good and you keep them slightly lubed with oil. It will wear though.
Black chrome is really the best option for fork tubes, though there is a black titanium process I'm waiting on word from my plater about. I do generally a run of plating a month or so and could probably arrange for black chrome....