prefer the simplest possible solution.
X10 seems to be ideal if you want to control devices all over your house,
but it's a lot more complicated than a single-chip relay driver connected
straight to the parallel port if you just want to switch a few lamps on
your workbench or whatever.
All the lights on my workbench have a switch, why not use that?
Personally I have two specific projects in mind;
Network printer power
I have half a dozen printers scattered all over the house, and they are
rapidly being connected to my home network. It would be real nice to leave
them all off until printing needed doing, then to be able to turn on any
printer remotely from any computer followed by powering down after some
reasonable interval. Laserprinters are right at the edge of what X10 will
handle.
Huge audiophile audio and AV system.
Same thing, half a dozen items that use a lot of power, ie amps, or get
used up (older gear with expensive to replace dial lamps), that should be
off most of the time, and I would like to power up fairly automatically.
Now its not too likely I will be running out to buy one of these $500 power
strips, but you can bet I will be looking for them in surplus etc.