Update on the helmet-for-big-head search.....
In an attempt to find a helmet to fit me at a reasonable price, I dropped an email to Predator helmets regarding their new "Lee 8" helmet which is "sized to fit the medium to XL heads". They replied that, yes it would fit my head 7 7/8. I found one for $99 including shipping, it showed up yesterday, and it actually does fit. It even has room enough to add the skinniest of the shims (a whole assortment is included.) I wore it all day today on a canoe trip, and it was very comfortable, light, and the visor works very well.
As far as protection goes.....the shell is quite soft, I can easily squeeze it together, and the padding is very thin, maybe only 5/16 inch or so. I have no doubt that this helmet is inferior to a Head Trip, Grateful Heads, FNA etc, but for what I am doing, it will be just fine, and is roughly half the price. (It has a sticker in the helmet that says it is not for class V, or VI paddling, thought that was interesting.)
Anyhow, if you have a big head, and are looking for a nice looking, comfortable, moderatly priced helmet that will probably fit up to size 8, this might be an option. If you are looking for some serious protection, I would probably consider one of the other brands mentioned above.