Feral Heads from Max Mini
It is pretty apparent that these are targeted at Space Wolves players but I have to ask - why? With the Space Wolf Pack box you get about 50 heads as it is. I guess you could also use these for Chaos Marauders but I think they come with a pretty nice selection as well.
I have been really impressed by the stuff form Max Mini that I have ordered and the Pirate Ork heads are just really tempting. I just kind of wonder why they put these heads out because it seems there is already plenty of selection for this kind of bit.