X10 home automation
On these pages you find my experience with X10 home automation.
What to use X10 for
X10 is the affordable product line for Home Automation. It uses the mains powerlines as communication channel between receivers like lamp modules (dimming lamps) and appliance modules (switched power) and transmitters like minicontrollers or remotes. Most anything that can be controlled by the mains can be controlled with simple X10 devices. The fun starts when computers are added. With adequate X10 hardware and a PC with smart software you can build a smart house that improves comfort and security.
The theory of X10 is described in wikipedia.
For more X10 info, visit the X10 wiki
A large collection of X10 diy articles (some based on information from here!) at Ido Bar Tana's Home automation site