Unfortunately, Apple doesn't allow SD card expansion and even the camera connection kit is limited in utility. If you haven't decided which model of the new iPad to buy, or if you wish the iPad or or iPhone you already own had more storage, you might want to consider the Wi-Drive from Kingston
With this gadget, you can store movies, photos and more on the device and connect your iOS device via wifi. You have to use their free app to access media files, and you can transfer the wireless files to local storage, but that storage is still only usable within the app. This way you could have several gigabytes of movies on the Wi-Drive and copy one or two at a time to the local storage, and delete as necessary. Otherwise you might not be allowed to use the wifi device on an airplane.
Speaking of wifi, you might be concerned that if you have to connect to the Wi Drive's private wifi connection, you would be giving up Internet access. The good news is that the Wi-Drive acts as a router, passing through your requests to the Internet, albeit slowly. You can even use AirPlay to send the video from your iOS device to an Apple TV!
is a sleek, compact portable hard drive about the size of an iPod touch. The battery lasts about four hours and recharges via miniUSB.
I found the connection to the Wi-Drive to be intermittent and slow, and not something I would want to rely on. It's a neat concept, but for now, I would recommend buying as much storage on your iOS device as you think you will need and can afford, as the cost is almost a wash between adding storage from Apple (when purchasing the gadget) or buying the Wi-Drive.