Julia's Cabled Headband
This pattern calls for aran-weight yarn, but I’ve also made it in worsted-weight yarn. It ends up a little narrower and you have to add a few rows to the ribbing at either end of the piece.
My teenaged daughter loves wearing knitted headbands, though they are probably more decorative than functional in the cold Canadian winter.
Feb. 1 2009 update: Please note that a correction (number of cable repeats) has been made to the pattern.
Jan. 13 2011 update: Ravelry member ignia has created a very useful chart showing all the pattern stitches. You can find a link to it in this blog post.