WD makes a great product, the Passport Wireless Pro. It has a 4 GB hard disk (I think, but a pretty big disk). Once it is set up, all you do at the end of the day is take the SD card out of your camera, put it in the Passport slot, and it will automatically back up all the new files. You can just go to dinner and let it work. Then, if you have a problem with the SD cards, you connect the unit to your computer, via wifi or a cable, and there are your photo files.