The one "special coating" I've seen is carbon fibre to prevent glazing.
http://sycpowersports.com/index.asp?...id=66&incid=29
Not sure how well that works, but they do make performance carbon fiber brake pads. So that does seem to have some merit as far as friction performance goes. Not too sure about the anti-glazing properties though.
I don't think the fancy cut outs have much to do with performance. More of a weight reduction and better cooling affect. Less rotational mass and less steel to retain heat are always a bonus.
And this one is supposed to have "ribs" for better heat dissipation.
http://www.shop.kidnmekarts.com/Clut...0cc-Ribbed.htm