Portable Device to back up Digital Camera in the Field

We send engineers into the field to investigate damaged buildings. They take hundreds of digital photos each day. We recently had an SD card fail after the photos were taken, thus we are searching for a portable device to allow them to copy the photos to it at the job site thus giving us two copies of the photos, of which at least one should always make it back to the office for uploading to our databases.

We've found products from Wolverine and Hyperdrive, however they aren't quite right.  Also thought of a portable music play like the Zune, however Zune claims we can not connect the digital camera and the Zune directly to copy photos.

Is anybody aware of a small device which would allow us to :

1: copy photos to it directly from a digital camera
2: Allow review of the pics on the backup device
3: preferably be solid state: no hard drive
4: can operate using a car's lighter for power
5: Be small/light


Thanks for any and all suggestions.


Paul