If you are talking about backing up PCs in the field I would just a Ghost CD, or a specially built floppy if you need to add additional drives. Most are on the CD. Carry a USB external hard drive. Put a plum drive in it and the Ghost CD will recognize and be able to save to it at a decent speed. I did this all the time in Vegas for my customers. I would then burn the data to a DVD or CDs for them to keep if they wanted it. Which I did after the service call. Actually i still do that at home for my own backups.
I'm hoping for a solution that lets me image a whole server with, say, DVD-size chunk files. I could burn those later (after I moved them off my USB or firewire hard drive) and then when disaster hits, boot to the first DVD and keep feeding it DVDs until it was restored.
So far, I haven't found an open source solution for this yet.
