ecu locations

Ecu locations, what are they, and why would you need one. I found a listing on eBay and it confused me a little until I googled it and this is what they do.

They seem to be a chip that can tune a car to a higher BHP which will effectively give more power and make you go faster. It would really only give a small difference to the speed of a powerful car but if you are into racing then it could be the difference into whether or not you beat your mate in the same car or you beat that car that is always just beating you by a second or two.

Would you spend money on this?