In looking through the list of coded deities and keeping in mind the 'flavor' of the barbarian class within the setting, I've narrowed the field. Here, along with the justifications I had in mind, is a list of coded deities I can imagine a barbarian feeling enough connection with to follow.
Ilmater - For his dominance over endurance and perseverance, both traits that would be highly valued in a hunter-gatherer society exposed to harsh elements and a need for survival. Perhaps not the strongest argument for, but I could imagine it.
Selune - I imagine this as fairly self explanitory once one gets past the idea of a barbarian following a goddess. Keep in mind that not all mythical barbarian societies were male dominated (e.g Amazons). Having navigation, stars, moon and non-evil lycanthropes in her portfolio gives alot of reason she would be admired by primitivistic mage-fearing cultures, particularly coastal ones.
Lathander - His portfolio reads like a good-aligned barbarian's wish list.
Meilikki - Quite fitting in a non-patriarchal good aligned barbaric society.
Before leaving the good aligned deities, I should mention I left out Chauntea since in all setting accounts I've seen, barbarians have been strictly nomadic societies. Nomads rarely have time for agriculture, but I imagine someone could make a logical argument for her suitabiility.
Tempus - well, naturally.
Kelemvor - I hesitate here somewhat, since his lawful nature conflicts somewhat with barbarian tendacies to chaotic alignment but in the end I imagine death as an every day common fact among barbaric and nomadic societies and could justify a following. Death gods are always a major consideration in real-world nomadic cultures, it just seems natural that it would be so in fictitional ones as well.
Malar - Imagine, if you will, a marauding tribe of Barbarian Malarite lycanthropes razing frontier villages to the ground. Comes pretty easy to mind, no?
Talos - Portfolio reads like an evil-aligned barbarian tribe's wishlist.
Umberlee - Seems like a natural choice for coastal or seafaring evil-aligned tribes.
A great variation in traits and religions between tribal societies leads to a wide and varied type of barbarian. With a little imagination I'm certain even a few of the gods I haven't included could be figured into the picture somehow.
All of this of course, just my musings. Please do read it in the purely subjective manner it was written.