Some power strips include a master switch to turn all devices on and off. This can be used with simple devices, such as lights, but not with most computers, which must use shutdown commands from the software. Computers may have open files, which may be damaged if the power is simply turned off.
Some power strips have individually switched outlets.
"Master/slave" strips can detect one "master" device being turned turn off (such as the PC itself in a computer setup, or a TV in a home theatre) and turn everything else on or off accordingly.
Remote control strips are used in data centers, to allow computer systems or other devices to be remotely restarted, often over the Internet (although this leaves them vulnerable to outside attacks).