I made this hat and scarf set for the Make Me a Scarf swap and got a few requests for the pattern, so here it is! (I made it up myself, so no copyright problems here, folks -- go crazy!) Please post pics if you make one of these! I'd love to see more versions.
I used a chunky yarn from an unravelled sweater and 9mm needles. Guage is not really important here, but the cable (especially on the hat) looks great with a chunky. You could probably do a great version with two strands of worsted held together.
THE SCARF:CO 21 stitches. Work 6 rows garter stitch (3 ridges)
row 1: K4, P2, K9, P2, K4
row 2 (and all even rows): K3, P1, K2, P9, K2, P1, K3
row 3: K4, P2, slip next 3 stitches to cable needle, hold in front of work. K3, then K3 from cable needle. K3, P2, K4.
row 5: repeat row 1
row 7: K4, P2, K3, slip 3 to cable needle, hold in back of work. K3, then K3 from cable needle. P2, K4.
repeat rows
2-7 until desired length. Then work rows 1 and 2 one last time. Finally, finish off with 6 more rows garter stitch, BO, and weave in ends.
THE HAT:Same yarn, same size needle. (I like to use a 16 inch circular for the hat part, but you'll also need either another circular or a set of dpn's to finish off the top of the hat when decreasing)
make the band first:CO 13 (with provisional cast on is best, so you can kitchener later, but a regular cast-on will be okay, it just means there'll be a seam)
row 1: K9, P2, K2
row 2 (and all even rows): P2, K2, P9
row 3: slip first 3 stitches to cable needle, hold in front of work. K3, then K3 from cable needle. K3, P2, K2.
row 5: repeat row 1
row 7: K3, slip 3 to cable needle, hold in back of work. K3, then K3 from cable needle. P2, K2.
repeat rows
2-7 until band fits around head. You may have to end in the middle of the pattern to get the right length. It's okay. No one will notice but you that your cables do a little jog at the back

join band into a circle either by kitchenering or three-needle bind-offing from your provisional cast-on stitches, or just sew the two ends together. Check again to make sure it fits properly without stretching out the cable. It should not be too snug. Fix it now if it is not right!
upper part of hat: Pick up stitches on a 16 inch circular or dpn's around the top of the brim. You'll be picking up around the salvedge edge, so only one knit stitch will end up showing. Pick up 3 stitches for every 4. (I do: pick up 3, skip one...)
Knit in the round until the hat measures 6 inches from the bottom of the cabelled band. Be sure to measure from the highest point -- the dimple between cables, not the rounded out part.
Count your stitches. Decrease one or two if necessary to get a multiple of 7 or 8.
begin decreases for crown:if you have a multiple of 8:
[K6, K2tog] around. Knit one round. You now have a multiple of 7. Continue here:
if you have a multiple of 7:
[K5, K2tog] around.
K 1 round.
[K4, K2tog] around.
K 1 round
[K3, K2tog] around.
K 1 round
[K2, K2tog] around.
K 1 round
[K1, K2tog] around.
K 1 round
[K2tog] around.
K 1 round
cut yarn leaving 6 inches, and draw through remaining stitches. Pull tight and fasten off. Weave in ends.
***my hat has a little nubby at the top. If you like this and want to do it, stop decreasing when there ar 6 or 8 stitches left. Knit a few rounds, then finish directions for decreasing.
(my picture doesn't show the nubby bit, I've noticed -- you can see it in crochetfairy's post here:
http://www.craftster.org/forum/index.php?topic=127619.30)