Similar to the practice of multi-million dollar enterprise systems, WD's hybrid technology utilizes the concept of tiered storage.

ENGADGET: Western Digital builds 5mm-thick hybrid hard drive, Ultrabook makers sign on early

The cloud-storage concept is catching on in lots of ways, but music, as buzz about Amazon's new service shows, seems to be the next frontier in this cloud expansion.

CNN: Why cloud storage is the future of music

As with hydro storage, efforts are under way to adapt the basic concept of CAES to make it more efficient and easier to install.

ECONOMIST: Energy storage