A friend of mine sent me a message earlier. They've just bought a house in Yorba Linda and apparently are looking for new kitchen appliances, including a new refrigerator, which means they're doing due diligence on the models they're considering.
The IM has been lost to history, but it amounted to, “Why the hell would a refrigerator be kosher-certified?” Sure enough, Viking sells a range of appliances, including refrigerators, that carry the Star-K hechsher, that is a stamp of approval in the form of a K in a star that means that this has been approved for use by the Orthodox.
The jokes just spring to mind here: hermetically-isolated meat and dairy compartments, automatic fuzzy-logic pork rejector, chazerai detector (“It's Tu B'Shevat, eat fruit instead!”), in-door chicken soup dispenser, etc.
Seriously, though, there is logic behind the need to have kosher appliances. Kosher, in this particular case, just means “fit for use”, and specifically fit for use on shabbat, the Jewish Sabbath that runs from Friday sundown to Saturday sundown.
There are a huge number of prohibitions on the Sabbath, which fall into thirty-nine specific categories. Use of a water filtration device is forbidden (it's called borer, with the stress on the second syllable, and means “winnowing”, as in the winnowing of wheat from chaff); salting meat is forbidden (m'abaid) as a related activity to tanning hides (don't ask). You can't carry food home from the store, because not only is that causing the store employee to transgress the Sabbath, you can't carry items from a public domain to a private domain (hachnasah) or vice versa (hotza'ah).
Not only are baking and cooking (ofeh and bishul) forbidden, but it's forbidden to light (ma'avir) or extinguish (mechabeh) any kind of fire. This includes electricity, which brings us to the problem of refrigerators. Normally, the refrigerator sits there and only consumes electricity according to its own needs, which are not controlled by any human.
When you open a refrigerator, though, you are controlledly letting cold air escape and the compressor comes on as a direct result of your trying to figure out if anything tasty has been added to the refrigerator in the twenty minutes since you last checked it. In addition, your action of opening the door has the direct result of causing the light to go on. This wasn't a problem twenty years ago, because you could tape over the button that completed the circuit to the light bulb and the compressor. These days, unfortunately, refrigerators are smarter than that, and the mere act of walking past some of the luminescent displays can cause them to turn on. All of this, however, is chillul shabbat–profaning the Sabbath.
With ranges, the problem is actually the opposite. The ever-resourceful Jewish people have developed an entire range of (delicious, incidentally) dishes that are meant to be long-simmered or very, very, very slowly baked, so that they can be put in a warm oven or over a bare simmer before the Sabbath candles are lit. Braised meats and the stew known as cholent are products of this ingenuity.
These days, however, ranges have a safety switch that turns the range off after a period of time, six or eight or twelve hours. This is a great solution if you're absent-minded and leave for vacation with the oven on, but a problem if you put the cholent on at 4 p.m. on Friday for Saturday lunch and at midnight the flame goes out, since you'll have cold and uncooked food and no way to light the fire.
The solution is to have the manufacturers design a (usually obscure and complex) set of keypresses that can put the appliances into Sabbath mode. This keeps the fire from going out on the range and either suppresses the refrigerator light or keeps it on continuously.
Several manufacturers make ranges, ovens and refrigerators that can be programmed into Sabbath mode, and they're not all fancy. Viking is at the top end of the list, but your cheapo Sears Kenmore oven has a surprisingly complex set of Halachically compliant commands (that is, commands acceptable according to Jewish religious law). For example, setting it to Sabbath mode will disengage the auto-off, the light and any feedback sounds such as beeping or flashing. Simple enough, but holding various buttons on the screen will change the temperature at some random time after the command with no feedback whatsoever. Since the randomizing factor interrupts the direct action of changing the temperature, it's okay to do.
These commands are normally built into the models; you don't necessarily have to go and order the Sabbath-enabled version of a refrigerator, but not all models have a Sabbath mode.
As the rabbis say, if being Jewish were easy, everybody would want to do it.