I am looking for a cost efficient way to switch four 220V/100W PAR80 lamps in a light effect device from an Arduino digital output port. My initial idea is to use a TIC226D based TRIAC circuit but this would require a pcb and I was wondering if there is a more integrated solution? What would be your recommendations?
Try - http://bit.ly/hzn9iX ? - a four relay panel for $12.50 (at time of posting 
AC250V 10A per relay
---- update ---
note the 8 relay board is opto isolated, might be a hidden requirement 
That sound good and yes, the opto isolation is a requirement. Do you have information about the relays used on these boards? I could not find any details and wonder if they can handle the fast switching frequency of a disco light effect device (up to 0.25 or 1 Hz I assume).
You should contact the shop with these questions, I have contacted them once and had an answer in a day.
Found this after reading the number on the enlarged image - http://www.lemicro.cn/rar/SRD(T73).pdf
looks like the same family or Relays
If using low voltage DC relays to switch the AC lamps, why also a need for optoisolation? Electomechanical relays offer similar isolation value from the coil to the contacts as a opto does between it's input and output.
Lefty
Would it be possible to drive Solid-State-Relays like the Sharp S202 S02 (http://sharp-world.com/products/device/lineup/data/pdf/datasheet/s102s02_e.pdf) directly from an Arduino port? Or do I need a transistor or other driver circuit?
reibuehl:
Would it be possible to drive Solid-State-Relays like the Sharp S202 S02 (http://sharp-world.com/products/device/lineup/data/pdf/datasheet/s102s02_e.pdf) directly from an Arduino port? Or do I need a transistor or other driver circuit?
Yes you can use that with an Arduino output pin. The device has an internal optoisolator so you drive it just like you would a led. Arduino output pin to series 250 ohm resistor, other end of resistor to pin 3 of the device, pin 4 of the device to ground.
Lefty
Great! Thanks!