The DHT-22 is a low cost humidity and temperature sensor with a single wire digital interface. The sensor is calibrated and doesn't require extra components so you can get right to measuring relative humidity and temperature.
Posted by Hercules on 6th Jun 2012
very helpful company, excellent sales and tech team
Posted by Gareth Halfacree on 26th Sep 2011
The RHT03 (the actual product supplied, which is identical to the DHT22) is quick, accurate, and works on a single wire - but it's also pretty expensive.
There's a full review - plus a link to an Arduino library for communicating with it - over here: