Head-butting isn't something that happens often in hockey. It's one of those things you notice in the NHL Rulebook and go, "oh, I guess it's there just in case." That "in case" might just refer to Patrick Kaleta of the Buffalo Sabres, noted head-butting enthusiast.
Seriously, did you watch that Brendan Shanahan video above yet? If you haven't, do it now. Kaleta has head-butted like three dudes recently. The most recent was last night at First Niagara Center, when Kaleta ran his annoying little head into the face of Jakub Voracek. He's been suspended four games for that hit.
Kaleta doesn't really like the Flyers all the much, which Puck Daddy outlined pretty well this morning. I'd say the feeling is mutual. He's just one of those players that's just a detriment to the game. His job, which he does well, is to just piss people off and draw penalties. Not sure there's any actual hockey skill there. Hell, even Matt Cooke has some hockey skill.