Planning to play with thermometers, I've bought some Dallas 1-wire sensors: DS18B20 (plenty of examples on the web).
The sensor pinout is the following one (from the official datasheet):
The sensors are to be used in bus configuration:
with a 4K7 (or less, in case of long bus wires) pull-up resistor on the data line.
After breadboarding, I'm ready to play with this excellent "Dallas Temperature" Arduino library:
Here's the code I've used to play on the breadboard (showing temperatures through the Serial Monitor on Arduino IDE):
(compiled with Arduino IDE 0022)
I've also added an external LCD to have a first version of a working thermometer (more thermometers to come...):