While I don't personally own anything that requires batteries... If I did, I'd totally pick myself up some Sanyo eneloop batteries. They're eco-friendly since they're rechargable, they're colourful... Not to mention there isn't a cuter way to check the state of your batteries!
Shaped like a dog, the eneloopy lets you know if your batteries require charging. "When you place your eneloop batteries into the device the dog's nose will light up: green for fully charged, orange for partially charged, red means your battery needs charging and no light means you have a dead battery on your hands."
Not sure if they're only available in Japan, but according to DVice eneloopy launches this weekend!
Random, but too eco-cute not to post ;)