Something like
this .
I've never used one but they seem to work from what I hear. They are usually called "Smart Power Strips". You plug a main device into a special outlet on the strip. Then your other devices into the other outlets. The smart strip has a relay that supplies power to the other outlets when your master device is on. I believe it does this by sensing the current flow to the master device. Just make sure it is rated for the power you need to plug into it.
Others may be along that have actually used these, or have alternative ideas.
