There have been any number of times that I've been out somewhere, for example, at a client's office or a friend's house, and wanted to charge my iPhone 5S but the only cables around had 30-pin connectors. This will be a problem for me no more now that I have a Nomad ChargeKey.
On one end of the ChargeKey there's a standard USB plug while at the other has a Lightning connector. The ChargeKey is the same size as a house key so it fits nicely on your keyring is and it's made of a flexible, rubbery material only 2.5 mm thick.
Nomad also offer another version with a micro USB connector instead of a Lightning connector which makes it compatible with the likes of the Samsung Galaxy, HTC, Nexus, Windows Phone, and BlackBerry.
And if you'd rather have a design that will fit in your wallet, Nomad has the ChargeCard for iPhone 5/5S which is the size of a credit card and about twice the thickness (as with the ChargeKey there's a version for devices that use a micro USB port).
All of these products are priced at $25. For the roadworrier who fears his or her electronics might run out of juice this gadget is great insurance and gets a rating of 5 out of 5.