I've seen (and knit) quite a few hats but this one just popped out at me and I thought WOW! That is a cool idea! This hat pattern from the new book Mittens and Hats for Yarn Lovers: Detailed Techniques for Knitting in the Round features a cable ribbed edge. Cool...uh warm...actually!
Click on these pages from Mittens and Hats for Yarn Lovers: Detailed Techniques for Knitting in the Round to enlarge and read the full pattern for a cable ribbed edge hat.
More about the CPi book:
This book goes beyond a collection of projects to teach the reader useful information about the yarns and stitch patterns. Every project in Mittens and Hats for Yarn Lovers teaches the knitter something unique about the yarns/fibers that are used. Lessons are learned by knitting mittens and hats for kids and adults. Styles include quirky, perky, classic, and luxe—something for everyone. Contains 25 to 30 projects with variations knitted in different fibers, color combos, stitch patterns.
Carri Hammett owns a successful yarn shop and has an extensive background in fiber arts. Her shop is wildly successful because she stays ahead of the trends and constantly encourages her customers to try new things.