Saving power by switing-off the computers

Some time back I read an article suggesting we can save lots of power and make earth better by just switching off the computers when not using. There may be definitely many challenges. One which I faced was how to access my home m/c (for that matter any other) remotely if I switched it off. There is possibility that no one will there to switch it on when required. But it can be solved in a very simple way. Put in place a simple proxy hardware with every m/c which is part of the network and become active when m/c is switched off and vice versa. Any one willing to log into his/her remote m/c which is off can do so by first logging into this small component and giving command which will switch on the computer. Afterward, same story which all of us know.