You can get very portable and lightweight USB-based hard drives. They are the tiny ones, a little bigger than a pack of playing cards (not Identical but similar). Just checked the specs - 3"x5" and 0.5 inches thick. 5 ounces (140 grams). I saw some of these recently for $50-60 for 320 GB-500 GB. Get the kind with the 2.5" hard drive inside, not 3.5" if you want light weight and portability. Plugs into any usb connection and is powered via the usb. Unfortunately won't work with an ipad unless you can get usb connectivity (maybe the camera connectivity kit dongle
).
I gues you could stop by an internet cafe and use a computer to copy files from the SD or other memory cards onto the portable hard drive for backup.
Or just get a $200 netbook.
Comes with a built in hard drive, usually 160 gb or 250 GB. Wireless, a keyboard, etc. Of course it wouldn't make sense to me personally to carry an ipad and a netbook if one was trying to travel internationally and pack light.