@jmelesky/Curious - Very good points. I'll have to go back to go back to the drawing board on Superstition; for low-level Barbarians who can't rage-cycle yet, I still feel that it's a terrible and possibly fatal rage power, but for ones who can through one way or another of immunity to fatigue/exhaustion, it's not that bad.
As an aside, I also post on the Dreamscarred Press forums where they were talking about a proposed psionic power called Alienation that forced you to save whenever a spell or power was cast on you; it was debated whether that was too powerful for a 4th level power.
@deuxhero - I just put it up as a joke, but I'm sure there are ways taking a level of Wizard might help a Barbarian build. There actually is a decent reason to get a familiar in as a Pathfinder Barbarian: Familiars share you BAB, and their health is equal to one half yours, meaning a Barbarian's familiar will have about the health of the average Wizard XD
@Blyte - How much damage are you doing on the average attack?
Obviously it becomes a lot better if you've got a party member specifically buffing and protecting you, but that is a resource that every Barbarian isn't going to have. Also note that enemies still get the bonus on ranged attacks where you will be unable to take your AoOs against them - or Large or larger creatures (or creatures with reach) - or if you get disabled - or on spells/powers with ranged touch attack rolls. I can agree that it can be a very powerful in the right situations, but there are (over the course of the campaign) going to be many more attack rolls on your character than on any one enemy.
Still, you're right that it's better in more situations that I made it out to be; can you post your build(s) here? I'd like to run some simulations with a real Barbarian that has seen play.