I'd point out that iodine deficiency's effect on IQ seems to be entirely prenatal - that is, there is a window of vulnerability during a human's development, and once they're past that, iodine deficiency no longer operates on IQ (for better or worse) and all that's left are more minor effects like reducing goiters. Seems possible that a lot of nutrients are like that: main effects of deficiency are in childhood/infancy/prenatal.
When my iodine levels get low I develop symptoms of diabetes. Sushi can induce insulin shock/hypoglycemia in me.
It screws with my hunger and thirst levels as well.
Apparently I'm not alone, either; there seems to be some evidence that there's a link between iodine and diabetes more generally.
Rob Rhinehart's food replacement Soylent now has a crowdfunding campaign.
If you're interested in one or more of these benefits, send in some money! There is also a new blog post.