With the growing interest in ecological living, there are a few companies selling Electric Power Savers now. Actually EPS stands for Efficient Power Systems (web site doesn’t work well in Firefox—actually not very well in IE either), a trade mark of the company of the same name that makes them.
These devices purport to save power. They are plugged into any socket in your house (i.e. in parallel with your appliences not series) and claim that they can reduce your house power consumption by 10–20% by “a combination of filtration and correction techniques to improve the efficiency of various appliances and circuits.”
Well I say that a device plugged into one socket in your house cannot affect the consumption at a different socket any more than you can affect the electricity usage of your neighbour. The best it can do is act as a surge/spike suppressor by absorbing them and even then its effectiveness will depend on the electrical distance from other devices; on a different ring, for instance, will reduce its effectiveness.
Their FAQ points out that people with accurate usage meters have noticed that it is consuming some power—I am not surprised.
Think before you buy.
Update: Croydon Trading Standards are aware of the scam. See right at the bottom of this link.