Following on from this post, I have added a second sensor and developed the code further.
Here is the BMP180 (link to data sheet hosted with Adafruit), its a bosch sensor which will measure pressure and temperature – I bought from China via ebay – x2 sensors cost $2.96 delivered.
I outputted both the DHT22 and the BMP180 temperatures in the serial monitor to check to see how close they were – not too far out.
The board now looks like this:
The top line of the 16×2 is from the BMP180 and the bottom line is from the DHT22.
This is the BMP180 sensor