Concept

Most people have numerous hard disks and peripheral storage devices. This software application will be like a backup-tool that creates virtual folders which are redundantly raided/mirrored across multiple devices.

The all files placed in the folder will be transparently archived in compressed/encrypted/parity-checked/redundant files. (More specific file selecting is possible -- the archive will be overlayed on the current namespace in that case, and will only monitor files that match the selection rules.)

Usability enhancement

Files are assigned priorities based on rules (and possibly an info-queueing system). Those priorities will define how redundant files are.

It could also automatically mirror certain files to flash drives or cellphones, or other computers.