i've just done this tutorial: http://www.arduino.cc/es_old/Tutoriales/Rele
it works great! i've done it in a breadboard (with two 5v circuits for test) and then soldered (for just does not have 220v on a breadboard) and it works well for 1 light.
now i need more lights and i thought to make a relè for switch on/off a multiple adapter.
the thing i want to know: the pin of the relay are thin (just all other 5v-breadboard-based component) and i thought that more volts you have more bigger have to be the wire.. how many normal 220v ac light bulb can i control with one relay?