PICAXE 28X1*
7 LEDs (6 Red and 1 green) with 330ohm resistors
74HC595 shift IC
DS18B20 thermometer device
4k7 ohm resistor

* The code takes up only 29 bytes or programme space and requires only 3 outputs and 1 input pin so this should work on all PICAXE chips that have the READTEMP command.

It's actually very simple! The temperature that is read using the READTEMP command is already in binary format, all we have to do is send it to the LEDs. Rather than using 7 outputs from the PICAXE we use a 74HC595 shift chip which can act as up to 8 outputs and only requires three outputs from the PICAXE. In fact the 74HC595 chips can be cascaded (joined together) to give 16, 24 or more outputs and still only require three outputs from the PICAXE.

In this project we're assuming the temperature will never get above +63'C (I think that's a fair assumption...) so we're only using the first 6 bits of the value (the red LEDs), the green LED (that isn't shown in the above image or video) is going to be lit by bit 8 of the temperature byte, the DS18B20 thermometer IC sets that bit if the temperature is negative.

Not sure really :( Maybe more lights and add some sounds :)