I was going to point out the Monica pattern too- perhaps you could use the same idea, but maybe just make it 1 1/2 times as wide and then knit 1, k2tog, k1, k2tog, rather than k2tog all the way across.
I think as long as you do the decrease fairly evenly over the width of what you want to ruffle, you'll get the right effect. But then I'm pretty new at this knitting thing, so... It did work really nicely with the Monica pattern, though.
Mommy to two wonderful girls
"I don't have to conform to the vagaries of time and space, I'm a loony!" -Campbell Bain (David Tennant) 'Takin' Over the Asylum'
OTN: Cabled Sweater
, arm warmers, kids' clothes