All of the Tau and Inperial Guard tactia online talk about the concept of bubblewrap. That is cheap, expendable units that stop your big guns getting assualted. So, for Tau it's Kroot and for the Guard, it's the humble Guardsman. Now it just so happens that the Space Wolves have a unit that would be perfect for this role - Fenrisian Wolves. Perfect for stopping your Long Fangs from being assaulted. Okay, they're quite easy to kill but if you're enemy are killing them then they're not killing the rest of your army. Plus, they're quick. If you're playing against a gunline you can send them off to tie up an enemy unit while you get the rest of your army into position. I'm not saying that they are the be-all and end-all in the Codex but they certainly have their uses and I'm going to give them a playtest over the next couple of weeks to see how well my Theoryhammer translates to the tabletop.
Oh, and they're awesome in Kill Team where there is enough cover for their 6+ save to not be too detrimental. Although they still aren't the most killy unit in the world.