I designed this very, very simple hat for the "learn to knit" post I wrote over at ONTD: Star Trek for Academy Week 2010. It would be a great first project for a new knitter, since it is in garter stitch, but is shorter than a scarf. It is worked flat, and minimal finishing techniques are required.
Length crown-brim: 20 cm
Circumference: stretchy and variable
less than 1 skein Lion Brand Wool-Ease Chunky (50-75 meters)
1 pair straight or circular needles, size US 11
Cast on 20 stitches using your favorite method. Cast on more for a longer hat, or fewer for a shorter hat. Do not join in the round.
Work in garter stitch (knit every stitch, every row) until the piece is long enough to comfortably wrap all the way around your head, then bind off. A shorter rectangle will be tighter, and a longer rectangle will be looser. Remember that garter stitch is stretchy!
Seam the two short ends of the rectangle together to make a tube. Then, using a yarn needle, thread a piece of yarn through the ridges on the top of the tube, pull very tightly, and knot.
Weave in ends, and wear proudly.