Offroad: Salvage Time

For the "Direct Actuation Example" (page 172 and following) I will have to deviate from the proposed course of action due to two reasons. First in germany we have a 230 volts AC power grid. That means I have to substitute the 110 volts power switch tails (SFE COM-09842) with a 230 volts version as proposed in one of the preceding blogs 230 volts power switch interface .
Second I would like to build an RF alternative where no direct connection between microcontroller/ XBee and the switching device is needed. For that project I needed only one additional (electronic) part and was to stingy to order it online and pay a multiple of shipping costs compared to the tiny electronic part I needed. I was surprised how much of "them" I found in my pile of old electronic devices waiting to be salvaged (you can find more about that here). Could you guess what I was looking for?
Details shortly.

Update:

I was looking for

You can switch a lot of things with the help of optocoupler. They have names like "4N35", "CNY17F-4" or "PC817". The special thing is that the circuits aren't galvanically connected. You can learn a lot of optocoupler here.