Very stretchy hat that will fit head of 20 to 24 inches easily. I may be adding a worsted version and a baby version. (For baby, simply use smaller needles, like size 5 and baby yarn).
UPDATED: See Feb 1, 2012 updated PDF.
ERRATA: Top of page 2, where it says “repeat rounds 8 and 9 until…. it should say ENDING WITH ROUND 8. When you end with round 8, the subsequent decrease rows will all start the decreases, each knit 2 together will be worked on a knit stitch. This is a small detail that improves appearance of the decreases.
I have not corrected this in the free PDF yet.