When you first see the $29 Nomad ChargeCard, you'll probably wonder what the heck it is. It's flat, black, and credit card-sized with an odd-looking prong that snaps out. Unusual, yes, but useful, as it's an ultra-thin iPhone Lightning cable.
It's designed to fit into a wallet or passport carrier just like a credit card, so you'll always have a charging/sync cable on hand. You can use the ChargeCard to charge any iPhone or iPad with a Lightning connector from any USB port.
There's also the $24.95 Nomad ChargeKey. It performs the same function as the ChargeCard, but comes in a form factor built for connecting to a key chain. Both are made of rubber and plastic, and are slightly bendable, which adds to their durability.
Note that these gadgets aren't chargers themselves. They're charging devices. You should also note that, due to their design, you only have a couple of inches from their Lightning connector for your iDevice to a USB port. If you need a cable that can be used with a wall charger, stick with a traditional cable.
If your iDevice won't last through an entire day on a single charge, and if you'll have access to a powered USB port, consider slipping a ChargeCard into your wallet or purse or connecting a ChargeKey to your keychain.