To people who have problems with X10 responding at LAN parties/etc.: its someone's computer power supply. I had a peowr supply that was eating the signal. When I moved my transciever off that circuit, I had partial control again. I bought a filter and put on that computer and everything was fine again. I can't remember what frequency range these things work on.
Also realize that you probably havew 2 legs in your wiring. My X10 works flawlessly in the winter and sometimes misbehaves in the summer. The difference? All of the 220V heaters that act as a bridge. Summer I stil have the oven and AC but they don't run constantly like the baseboard heaters.
Everything for X10 has a specific purpose. Lamp modules and regular wall switches are designed for incadesant lights and that's it. Appliance modules are for appliances including flourescent lights and halogen lights. Levington also makes X10 units and they are of better quality but at twice the cost. With all these coupons, its cheaper for me to just have a few spare units around and replace as I need to.
Lamp Modules also respond to All Lights On/Off commands. Appliance modules don't.
I do use my network printer. Why rummage into the closet to turn on the printer when you can just remotely turn it on? Was tempted to put the server on one but saw no point to it. Its always on anyway. Computers won't really work that well do to the ATX power supply.
I have the server running Homeseer and it randomly turns lights on and off when I'm gone on trips. I had my one neighbor so confused because she didn't realize I was gone for 3 weeks because lights would randomly turn on and off. There was even a script that made it look like I was turning lights on for a minute to move through a room and then the next lights popped on for a little bit. When I get a permanent IP address, I plan to add a webcam and X10 web server (yes you can control these things through the internet) to the mix so I can look in on the house every once in a while from the road. Plus on the odd chance I actually notice when my parents stop by to check in on the place, I can have some fun.
Add a motino detector or two and it'll make coming home even safer.