The other night I was reading Elizabeth Zimmermann's Knitter's Almanac in the bath (what, like you haven't?) and discovered a little project she devised to practice the technique of double-knitting. It's a little potholder from bulky wool, where the sides are made of garter stitch and the center is actually two layers of knitting, back to back, made at the same time. Such a quick little project, and me sitting on all that leftover wool from my cardigan... obviously I had to make it, and right then.
Out of the bath, I cast it on, double-stranded with the worsted weight Boysenberry wool, and in an hour or two, it was done: a thick little square of wool with two layers of stockingette making a little padding in the center. Very cool. And practical, since wool is such a great insulator and won't conduct heat like cotton, when wet. Not to mention it's totally inflammable.
Aren't sheep awesome?