DS18b20 Temperature Sensor and Wifi upload to a host to log temperature
A simple example of reading the temperature using the Arduino libraries and logging it to a web site.
I have built a bunch of these for different purposes. The web host software handles notifications, sms messages, graphing and any other use needed.
The DS18b20 is waterproof enough to have spent the entire summer 1 foot down in the lake recording the lake temperature.
The condo version has reported the condo air temperature for months on end with no glitches to provide evidence that the air conditioning does not work properly.