Simplest way for remote power control?
X10 is a good, reasonably inexpensive choice, whose standard has been around for a while, and thus has significant documentation and hobbyist examples available on the Internet.

For X10 projects/tutorials, you may want to start with this Instructable as well as this one.

Also, to learn more options, you may consider reading the book Smart Homes For Dummies, which provides background on a variety of options including X10, although this book is short on details for practical implementation.

That said, if you want to step the DIY aspect up a notch, you may want to invest your time learning to use an inexpensive hobbyist microcontroller board such as Arduino, and supplement it with some basic experiments with AC Relays. Then your options will really open up, including allowing wireless control networks, as well as power-on/offs triggered by sensor readings, status indicators, etc., limited by your creativity/requirements.