The DS18B20+ is a handy, 1-wire compatible temperature sensor, ideal for interfacing with the PICAXE!
The Dallas Semiconductor DS18B20+ is ideal for interfacing to a microcontroller, especially if it uses the '1-Wire' interface which allows looong distances between sensor and microcontroller (200'+!).
It is often used with the PICAXE microcontroller, which has the built-in function "readtemp" to communicate with this device.
The DS18B20+ features:
Packaged in a TO-92 (transistor-like) package, all you need is 2 wires - ground and DQ (I/O & power), or you can use the Vdd line to give it regular power input.