A cowl not only provides warmth but it can add a new dimension to a sweater or shirt. And this pattern from http://www.knitpicks.com/ is a great example:
Finished Measurements: 14" tall x 26" circ.
Yarn: Knit Picks Imagination(50% Superwash Merino Wool, 25% Alpaca, 25% Nylon; 219 yards/50g): Seven Dwarves 24361: 4 balls.
Needles: US 4 (3.5 mm) 24" circulars or DPNs
Notions: Yarn NeedleStitch Marker
Gauge: 24 sts and 32 rows = 4" in St st on US 4 needles
CO 312 sts. PM and join in the round. Work in Garter st (K 1rnd, P 1rnd) for 1".
Next rnd: K2tog around: 156 sts.
Begin Ruching Pattern: Work 1" in St st (K every row).
Next round, inc 1into every st: 312 sts.
Work in St st for 1".
Next round: K2tog around: 156 sts.
Repeat this sequence six more times.
This will give the cowl one smaller, flat end and one ruffled end.
For two ruffled ends, repeat the ruche sequence to the increase round.
Work 1" in St st, then work 1" in garter st. BO all sts loosely.
Weave in ends.