Only about 1.5mA of DC is needed to turn on and off 400 watts of AC or DC power to a load.
http://www.imagineeringezine.com/PDF-FILES/fetssr.pdf
The circuit uses an inexpensive C-MOS inverter package and a few small capacitors to drive two power MOS transistors from a 12v to 15v supply. Since the coupling capacitor values used to drive the FETs are small, the leakage current from the power line in
http://www.discovercircuits.com/PDF-FILES/fetssr.pdf
http://www.geocities.com/fishziblu/relayboard.html
http://www.4qdtec.com/srd.html
can switch up to 600 watts of 120vac power with 50 uA control current.
http://www.djandassoc.com/e-zine/ssr.html
controls relays from PC parallel port, includes some BASIC example source code
http://home.maine.rr.com/randylinscott/dec98.htm
Switch almost everything on and off with a simple mouse click. Some tech specs: relay outputs, on-board power regulator, on-board serial port.
http://www.nutchip.com/progetti/pc_out/pc_out_en.htm
turn relay on and off by hand clap.
http://home.maine.rr.com/randylinscott/dec97.htm