Andriasang has discovered that the 3DS Circle Pad, the peripheral that adds an extra analogue stick and a couple of shoulder buttons to the handheld, will last an absolutely mammoth 480 hours on a single AAA battery. That's not all that surprising when you realize that it all works via infrared, but it's still nice to know you're unlikely to be caught on a long journey without your second analogue stick.
The accessory, which works with games like Snake Eater 3D and Resident Evil Revelations, hasn't been particularly well received by the press, but in terms of sheer usability, you can't knock it.