This is an excellent question. I have had card failures on a trip. As someone says above, is it a dying market? I suspect so. Epson and Jobo (and others) used to make portable hard drives able to accept CF and SD cards to back up images. I suspect that the reduction in the price of cards means people just buy more of them, but that does not provide a back up unless one’s camera has dual slots (or one takes a netbook). Can one find them today; not that I have found. Epson makes a P-3000 Multimedia Storage Viewer, but at £350 it is more expensive than netbooks and with only a 40Gb HD is useless in the era of 24MP+ sensors.
I have a Jobo Ultra One Giga, which has a 80Gb hard drive, takes all the cards and is a simple back up device. Is 80Gb enough? No, I wish they made at least 320, but they are no longer made. It does not have an image view screen, but the simple screen does tell one that a back up is complete. I have used it (and still do) in Patagonia, Peru, NZ, Europe and only last year in Venice. It remains a key travel companion. For me, not wanting to travel with a laptop, it remains an invaluable tool. Pity it is no longer produced.
So, what to do? Buy a camera with dual cards slots and lots of cards; possible, but not sound advice if you already have a camera. Buy an inexpensive netbook and portable hard drive; more bulk than is necessary. Buy an ebay cast-off; reliability?
Anyone any other ideas?
Hope that helps.