I'm not much of a beanie fan, but this was just too hard to pass up. Over at the Google Store, you can purchase an official Google fleece Android beanie for $16.00 + Shipping. It is made out of 100% polyester, and gives your head two tiny green Android nubs to show off your favorite OS.
They come in infant, toddler, S/M, M/L, and XL sizes. The infant and toddler sizes are lined with cotton/spandex for comfort. All are the same price, but the adult sizes are going very quick - so if you plan on buying one, order now. And who knows, this could become a collectible! Their stock is depleting and no information on whether it will be available later.
If the Android beanie isn't quite your style, then they also have some other headwear below in the suggestions. And for those of you on a budget - the Android cap is only $5.50 + Shipping. Shipping could turn out to price higher than the cap, depending on your location.