Electrical usage control software

[Marq]

I was listening today to guys telling me about software (and presumably there is related hardware) that controls electrical usage. It does this by analysing usage and switches geysers and fridges on and off (I assume again as did not get details). They also talk about remote controlling switches.

It works on the db (does not require rewiring a home or installation?) and has a cost per phase coming in. There is a monthly cost to this installation which supposedly can cut your electricity usage from 10 to 30%

Does anybody know anything about this - like how it works, does it work etc?

[Katenda]

We implimented a Circutor system in our factory that control maximum demand and switch certain geysers, A/C's etc off as we require. The system can also be programmed to switch lights etc off on specific times.
The Nelson Mandela Metro use a "Ripple" controller that switch your geyser off when their demand is high by super-imposing a signal on your supply.
Do not know which of the two systems they want to sell you?