This Tank Calendar.
Bought the first ones, selling the other. Sorry for hawking wares on a site where you, the looker, come to expect vapid free entertainment but I love me some tanks and I spread the gospel of treads as often as possible. So if you need to keep track of the days while staring at an armored fighting vehicle you might want to buy one. Or ten. Also if you need combat boots that give your badly constructed feet (thanks DNA) some structure and make you feel just the slightest bit bad-ass those boots are recommended by all of the world-famous web-comic artists here.