Found this little beauty today while surfing. Would be pretty handy I reckon. Save you having to remember to disconnect your plug or isolate your fridge when you stopped.
http://rvelectronics.com.au/index.php?route=product/product&path=57&product_id=53
http://rvelectronics.com.au/index.php?route=product/product&path=57&product_id=53