I've been using this new Discovery Expedition vented fedora hat for a few
months now.
The extra shade it provides
compared to a regular hat makes it worth every penny of its 30 dollar
price, but the real advantage in my opinion is the all around screen
material on top. Combine 360 degrees of venting with the small space
the fedora shape creates between the top of your head and the top of
the hat and you've got some serious cooling of your noggin.
I'm guessing the additional
surface area of the brim has over twice the sweat absorbing power as a
conventional baseball hat. It's made in Sri Lanka and comes with a neck
strap that I deleted.