Davide Gironi published a new build an AVR ATmega328 based CO2, temperature and humidity logger and meter:
It logs data feed, CO2 in air in terms of ppm, temperature and humidity to a xively.com feed.
It also display realtime data to user through a 16×2 characters LCD.
This logger it is based on the xively logger you can found here
Check out the video after the break.