I haven't looked at the stuff in a couple of years but I used to have a lot of my old house running on X-10 stuff. Most of my light switches were X10, lamps had lamp modules, powerbar for my TV stuff was all hooked to an X10 module, coffee maker and I also had a motion detector set for night only so when I walked downstairs in the dark it turned on the living room light and the bathroom light.
The best use was a wireless light switch right by my bed that could turn off all house lights without me getting up or with the press of another button I could turn on the bedroom light in the morning, the downstairs lights and start the coffee maker in one go.
X10 is fun, cheap, easy to use and you don't need to pre-wire anything. On the other hand, it is not high quality gear AT ALL. Expect modules to stop working after a year or two and they don't provide feedback signals so you couldn't "accurately" tell what state a switch was in from your PC or web access.
All that being said, if you are doing it for the fun of it, X10 is the cheapest answer to many fun solutions of convenience. I didn't get into it again in my new house. I will probably look at better gear if I decide to do it again.
