Keeping your files in safe is very important. I have lost some files because hard drive failure. How about to lost your embedded device? You also lost your files, notes and everything on the device. Backuping data should be done on daily basis. Why it's done so hard, could it be easier?
What should be backuped. Notes, music, documents, images & photos, movies, game records, preferences and everything on the device which does not come by default. However there's no point to backup installed applications but their settings should be. So is it enought to backup users home folder? It should be a safe start. Good system and applications should save their data and settings to the user's home folder, but there might be also a memory card which should probably be backuped as well.
The backup device. Usually you want to backup your embedded devices to the desktop machine. Fine, let's do so this time as well. However some clever people might have USB port on their devices and might want USB storage devices to be backup target, but let's forget it. We need a software on the desktop machine side. It should probably support different backup versions, easy restore and storing backups to external media such as CD, DVD and tapes. Files would be nice to be accessed on the desktop machine as well.
The backup progress I'd like to see is: attach the embedded device to the desktop, press a couple of buttons, backup done. What are the candidates? I think there's not really any ready to ship software for backuping Linux based embedded device. Simpliest we could have a script which copies home directory to predefined desktop machine path with date information. Restore would be copying data back to the embedded device. More sophisticated solution would be preferred, since we could have different operating systems for desktop machine and single script would not work. Client-server type would be nice, having server on desktop machine, embedded device would simply contact to the server, transfer files and ask for restore. Server would handle archiving data, choosing correct backup to be restored, store files to external media, show files and all kind of stuff. Server for multiple operating systems, standard protocol for clients to talk. And why not to backup desktop machines as well. There would be a nice project for somebody, anybody?