From my exploration of crown down hats comes this generic, plug-in-your-numbers hat. This pattern can work with any gauge and any yarn, just prepare to do a little math along the way.
Description from Pattern:
This hat is worked in plain stockinette, but you could modify it slightly for an allover ribbing pattern or anything else you might fancy. It can be worked with any needles, yarn, or gauge that you want with a little math. All of the techniques used here (including the Turkish Cast On With a Twist instructions) and a crown down hat project tutorial can be found demonstrated on my blog at jmbain.wordpress.com. If you want a shorter brim, you will need to decrease sts in the rounds preceding it (about an inch and a half before the brim), so that the hat stays flush to your head.
The model hat was knit with Knit Picks Wool Of The Andes Sport in Forest Heather, with 2 1.5 US circular needles at a gauge of 6 sts/inch.
The pattern is availible as a pdf. file down below.