Have a look at the NANO.r00t-Ed site for some interesting projects including this LM34 Temperature Sensor Weather Station Project. It uses a LM34 temperature sensor which is similar to the LM35 that I used in the PWM fan controller project except it outputs voltages that scale with Fahrenheit instead of Celsius.  There is a microcontroller that reads in the voltage and determines the temperature which is sent to the weather station computer. For a bit of added fun some beacon lights are also able to be activated by the system! Full code and schematics are available.

“I made a circuit that reads the output from a LM34 (temp sensonr) and send the output to the computer using PIC12F683. I also used the project called phpWX to collect the weather on my area and displays it on the page.”