While at its heart this is a simple bottom-up beanie, the special feature of this hat is the four "ribs" that eventually meet at the top of the crown. These are achieved through slipped stitches that also conveniently hide the decreases.
The hat is available in five sizes -- infant, toddler, child/teen, adult small, and adult large -- and even the largest size uses less than an average skein of worsted weight yarn, making it the perfect pattern for that one skein of impossible-to-get-more handpainted yarn that's been in your stash forever or even (if you're making one of the smaller sizes) leftovers from a sweater project.
This hat has already become a favorite in my house (a certain toddler keeps stealing it from me!), and I hope it will be in your house, too.