The Space Wolves have an option in their codex that no model exists for: the Chooser of the Slain. Basically it's a token that confers certain benefits to the controller, while negating some benefits to his opponent. The rules state it must be smaller than the Rune Priest, but other than that you can let your imagination run wild. I really hate when GW has options in a book for which their are a) no models, and b) no clear definition of how they work, what size, etc...
That aside, here you go, my choo-choo-chooser:
|Chooser of the Slain Parts|
I started with the Raven/Shield combo from the Empire (Fantasy) General's box and a random Space Wolf helmet. I thought about trying to cut around the raven's feet in order to avoid excessive greenstuff work, but found no real way to make it work. So, I clipped off the feet and drilled holes into both the helmet and body of the bird. Then I stuck some small gauge steel wire into the helmet and bird. A little greenstuff work later and I have a bird (cyber-raven) perched on a helmet.