My first is this..
Rage feats. Sure we have rage powers but I mean something simple, like maybe the pathfinder equivalent of extend rage by giving you more points if you take the feat.
Everlasting Fury (General)
You can delve deeper into your pool of anger
Prerequisite: Ability to Rage
Benefit: Add 6 rage points to your maximum rage point total.
This kind of feat would help some of the barbarians without fantastically high CON scores.
Suggestion: It's not said anywhere but how about when you gain more constitution through natural means of level gain (4th lvl, 8th, etc.) you gain rage points equal to your barbarian level so it works sort of like hitpoints?
say you had 14 con to start, then at 4th you made it 15, then 16 and 8th level. Well now you would gain 2+3 rage points first for the level, right? Well now you gain 7 more for those last 7 barbarian levels.
More will come as I think of it ^.^