Fun fact: I never leave home without a microUSB cable. I have a short cable that stays in my bag at all times – you know, just in case. The need for charging and the like is constant, so it's hard to say when that cable could come in handy. Several months ago, a new Kickstarter campaign hit the scene that could end my need for a USB cable in my bag, and instead put one in my wallet. I'm talking about ChargeCard, a project that ended up getting more than triple its $50,000 target goal.
Here's the gist: it's a credit-card sized device with a pop-out full-size USB plug on one end, and (in this case) a microUSB plug on the other.