Controlling 110V lamp using Arduino

I searched the internet but could not find great help

What did you use for search terms?

http://www.google.com/search?q=arduino+x10

These are from the first page...

http://www.arduino.cc/en/Tutorial/X10
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1243974689
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1239988351
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1217562002
...