Have you thought of multiclassing into the new prestige class Rune Scribe? This would make for an excellent Barbarian Shaman. I think the Barbarian could make use of all the verstility Rune Scribe brings as well as make his weapon attack more effective (No necessarily more damage, but the Fire rune does increase your average damage by allowing rerolls). the Earth Rune give you bludgeoning weapons the change to prone without save, I find that simple amazing. It's actually better on something with a low damage range like a sling. 1d4 damage means you will hit max damage 25% of the time and autoproning them. The Wind rune gives you flight and fall insurance as well as a knockback range attack with no max range, just anything you can see. Eagle eyes let you a mile. You can have some fun with that for sure. and Finally the Ice rune give some great utility. And in emergencies you have access you the sleetstorm spell. Which let you make an area heavily obscured, which allows for hiding and has a chance to break concentration spell casters. These are all useful Runes for a Barbarian. Going all 5 levels gives you a lot of new abilities after attunement to all 4 runes.