TwelveSouth's PlugBug might be the answer to your question. How do I charge or power my MacBook and other iOS devices at the same time. with PlugBug you can charge your iPhone and you iPad at the same time. It is one device that lets you charge two devices at the same time. Snap PlugBug onto your MacBook Power Adapter and you now have the first ever device that lets you charge your MacBook + iPad or iPhone simultaneously, from one wall outlet.
Comes in very handy and is useful for international travelers to the US and Canada. As it can be used to convert an international MacBook power adapter into a North American power adapter. It also acts a bonus USB charger.
Price: $34.99