Hi, The best way to control lights and many other things is with relays. They will work with 115 or 230V lights, incandescent, fluorescent or CFL or Low Voltage.
Optical isolation is good; many low-cost relay boards have isolation.
For lots of How-To on controlling power with Arduino see the http://ArduinoInfo.Info WIKI http://arduino-info.wikispaces.com/ArduinoPower
Web Interfaces: I have only sent data to the web so far. There are examples that use Cosm.com to send Temperature and Humidity data etc. here:
http://arduino-info.wikispaces.com/Cosm-Arduino