Woolly Wormhead's 2012 Mystery Hat KAL, the idea is that you buy some suitable yarn and knit as instructed- the instructions come in installments- and at the end of November you have a hat!
I'm planning on using this, but I have yet to buy it! Unfortunately I don't have anything suitable in my stash!
Will post photos as I go along!( As if I didn't already have lots of things to knit!)