That's really interesting. I don't think I've ever seen an MMO with a headbutt animation. As a dwarf, I would love to be able to do that. I can imagine it acting as a stun or knockback ability. And the higher your skill is in it, the less chance you have of damaging or stunning yourself.
The only problem is that we'd probably be too short to properly headbutt someone else in the head :P
Kicking vs Headbut
The first thing I think of is having to close the distance to execute a headbut while a kick is more like a 'ranged' weapon. This also opens up the floodgates. If we let the Dwarves get a headbut then the Ogres would want a double-handed smash and the so on and so forth.
-Todd
That seems like a pretty neat dynamic. I mean, you would be making the Dwarf Headbutt animation instead of the Dwarf Kick animation, and the Ogre Slam would be instead of an Ogre Kick. It might be slightly more complicated, but I don't think it would be a much more difficult task unless the Dwarf Kick and Ogre Kick animations were already finished (they probably are.)