Remi wrote:
I want a room thermometer that will instantly (or at least very quickly)
tell me the room temperature as I move from room to room. Is there such a
thing, and if so, where can I buy one? Thanks.

I don't know to what purpose you're planning on using this, but my
local utility company (the City) gives away little thermometers that
you can stick on a wall. They're similar to the little plastic forehead
thermometers you see in first aid kits.

You could probably get a few of those and just leave them in an
inconspicuous place in the room and glance at it as you go by.

Something similar to this: http://www.extra-mile.com/color/fever.htm
but mounted on a cardboard the size of a business card and calibrated
for household temperatures (50 to 90 degrees, I think)