Darklone: "He's dim but not dim enough (Int 3) not to know that he's not as clever as others. So he looks for others to tell him what to do."
I agree that if this character wasn't a power gamer, and didn't fall into the trap of playing the character as a stereotypical grunting barbarian, that it could be interesting. But I disagree with the statement that self-assessment and self-reflection are attributes related to Int. The ability to assess oneself is a Wisdom based characteristic, and IMO noone with below average wisdom correctly assesses themself. A low wisdom, low intelligence person assesses that he might not be so bright, might not have as much book learning, but assesses that he's just as good as everyone else and just as qualified to make decisions because of his 'common sense'. Low wisdom characters assess themselves as being more capable than they actually are. Overconfidence (or over excitability which generally ammounts to the same thing) and the associated lack of planning and reflection is probably the defining trait of low wisdom.
One of the reasons that this character would be so hard to play is that the typical characters of literature with low INT are often offset by relatively good WIS scores. Characters like Quasimodo, Forrest Gump, or Lenny or what have you have redeeming features like humility, empathy, intuitively strong understanding of good and evil, strength of will, and strength of character. These are all attributes of wisdom. They can be duped, but once they figure out that they've been duped, they do the right thing. They place thier trust ultimately in the right people, and when the people that they place thier trust in don't act faithfully they recognize it. A character with both low wisdom and low intelligence will lack the ability to act in a manner that is wise for someone with poor ability to discern cause in a effect. In other words, they won't even be self-reflective enough to realize that they don't make the right choices often and act accordingly to put thier trust in a person or moral code that can make the 'right' choices for them. Low wisdom people, whether intelligent or not, seldom learn from the mistakes they make in their life. They never seem to remember that fire is hot and keep burning themselves. Think of the absent minded professor type that no matter how many times he misplaces his glasses, or his checkbook, or his keys, can never seem to remember to put them in a place they can be easily found or to look in that place he always puts them. In the case of both low wisdom and low intelligence it is even worse than that. Granted, you can overplay how bad a wisdom 8 is (we all know a few wisdom 8 people), but it still means making the wrong choice more often than not.
We probably know a few people with 2 out of 3 mental scores at 8 or lower, mostly because we are nerds or hang out with nerds and know of the int 15, wis 8, chr 8 types. We might even know of a few int 15, wis 6, chr 4 asperger syndromes types, and hopefully we are all charitable toward them and think something like "I was alot like that at 13, and am a geek myself, there but by the grace of God go I."
We probably _don't_ know alot of people who have all three mental characteristics at 8 or less (unless you have been doing a stint in prison or alot of manual labor lately or are a social worker), and the best most of us can probably do is dredge up an example from high school. I happen to have enough of a character flaw (or low wisdom since D&D doesn't have flaws) that I've messed up my life from time to time and have hung out with quite a few people with three mental scores at or below 8, and I got to tell you that they wouldn't make particularly interesting characters for most people. They typically live very narrow, very small, very one dimensional lives. The best of that crowd is pleasant in a very irritating you always have to be patient with them sort of way, and so long as you never try to shake thier core beliefs to hard or threaten the ego that they need to sustain themselves you can get along with them ok. The worst of them are brutal in a way that most people on this board are going to find really hard to understand, and if anything its my suspicion that a 12-16 INT RPer isn't going to understand a 6 INT character with no comfortable literary strerotype to latch onto except for a semi-comic thug that causes me to not recommend this sort of character.
That and I've never seen anyone try to play one that isn't a power gamer trying to maximize how much butt he can kick in combat.