A couple years ago I heard some University wonk talk about the future of the electric grid, and the dude had a couple amazing ideas that I was just reminded of as I read about the latest electric cars being shown at the Detroit Auto Show.
Imagine you had a plugin hybrid or electric vehicle. Every night when you get home, you plug it in so it is fully charged for the following day. Now imagine that your car was plugged into your house in such a way that when there's a blackout, your home's electricity could temporarily come from the battery in your car! Sort of like the UPS' we attach our computers to in order to insulate them from the instabilities in our electrical grid. Neat, eh?
It gets better. Imagine your car was a hybrid and its engine could keep the battery charged while it's supplying the house. Now you can avoid the dark for at least as long as your car has gas! And, if you so chose, you could even feed ("sell") any excess power back into the public grid, potentially also helping your neighbor keep the lights on.
Now, let's scale the idea. Imagine that lots and lots of your neighbors had the same setup and imagine that you all have some deal with the power company that they can, during a severe power shortage, automatically start your engines (or at least start drawing power from your batteries) to help avoid brownouts. The grid becomes a self-healing distributed network of energy producers!
Having one's car battery act as a store of energy is also very enticing to those folks who simply want to become independent from the grid. I've, on several occasions, investigated adding solar power to my home. Since solar power is obviously time-of-day dependent (just like wind), most solar home owners can't really go "off-grid" because they need a way to keep the lights on at night and adding batteries to a solar installation is a large added cost. In most states, the power company is required to buy your daytime excess electricity, effectively becoming one large-ass battery for your solar installation. So that is fine - most of the time. If there happens to be a blackout during the night, you're out of luck. Electric/hybrid car batteries can provide this grid independence!
The above can all be done today - all the technologies exist. Neat, eh?