I was thinking I could lay one above the other, with something in-between so they stay separate - that way I'd be kept cool as well as the laptop. (It's been over 100°F / 38°C for the last few days now - and it's still not air-conditioning country...)
They do make ones that are meant to stack, too:http://www.amazon.co...-Rack/dp/B00BDSHCPE/
I don't know how stable that would be on your lap, though, since it was designed to sit on a counter that stays still.
Also, if the exhaust fans on your laptop is blowing hot air out of the bottom, it will likely cause you to be even more uncomfortable, blowing the hot air right through the racks and directly onto your lap. At least the cutting board I suggested would shield you from that and therefore could make you feel cooler.
You could also place an icepack or 2 on your lap, under the cutting board, without any worries about the coldness of it causing a condensation issue that could damage your laptop. The cutting board would be thick enough to protect the laptop from that. And while you might end up with a wet lap if it is humid, you'll be sufficiently chilled enough to not care how hot the weather is. In fact, you might need to take a periodic break to warm up and prevent frostbite.
One of these rolling pins
, filled with water and frozen, then placed on my lap while I am working or doing whatever (seated in a chair) is one of my summer survival tools. I have also been known to fall asleep hugging it during especially hot weather.
A 1.5 liter soda bottle recycled for this purpose would work, too, and you could keep a couple in your freezer, so you can swap them out periodically. That way you always have a frozen one ready to use while the other is refreezing. It could also adjust the angle of the cutting board to make typing more comfortable, by raising the front of the cutting board, rather than the rear of it.
And you might want to keep those frozen bottles in your freezer year round, if you have the room for it. Filling up the empty space in your freezer with bottles of water will save you money on your electric bill by preventing the compressor from needlessly kicking on so so frequently, as it tries to keep all the empty space cold. And in the event of a power failure, the frozen bottles will help keep your freezer cold and your food from spoiling.