>>16
That would be the most pointless thing ever. There would have to be a switch for each one individual one, because you would be wasting lots of power if nothing was plugged in. Even with something plugged in, it would be wasting power because it would be supplying all of the different DC voltage sockets. If you wanted it to handle something like a laptop, looking at my laptop's adapter it needs 20V/4.5A. So, this thing would need to have enough DC voltages that, if all put in series, they would at least be 20V. It would also need to be capable of providing the 4.5A. Each of these things would cost hundreds if not thousands of dollars, and they wouldn't be accessible because they would be behind the wall, at least until the thing gets so hot that it burns a hole through the drywall. I think its a little more practical just to use wallwarts for now...