“PlugBug is a 10W USB wall charger that piggybacks onto your MacBook Power Adapter, creating a totally unique, all-in-one, dual charger for MacBook + iPad or iPhone. That means you can charge your MacBook + iPad or iPhone at the same time using one wall outlet. Remarkably simple and elegantly designed, this go anywhere power pack means one less charger to carry and one less wall outlet to find. PlugBug simplifies your life in a way you never imagined.”
This device is pretty cheap if you own many Apple products and if this is an actual problem for you.