We consider the Air Temperature in Ward Cunningham's backyard to be the most systematic measure of sanity on the world wide web in any of its iterations. No gaslight here! Ahhh.
Live data is an experiment for Federated Wiki. Although the chart can be copied to other sites, it won't update there. Is this the expected behavior? Is it the most useful?
The thermometer is placed 18 inches from the east-facing lower-level of the house. Trees shade the sensor from morning sun except for an hour or two mid-morning. More elaborate reporting can be found in Ward's SensorServer 
site.
Try rendering with D3 Line.
Sensor placement
This page includes a chart item that contains a time series of data samples, the most recent of which is shown in the readout. The time series is updated by a cron script. The script transmits a Txtzyme program over USB to an attached Teensy micro-controller. This program signals a Maxium DS18B20 digital thermometer over their one-wire protocol. Return data is translated to Fahrenheit by the script and then edited into the flat-file JSON representation of this page.
We generate the following reports from flat files maintained within the SensorServer system with the mksensor script.
Txtzyme extends the reach of the USB bus to arbitrary electrical signals. It interprets throw-away programs encoded as single-character commands bundled into short strings transmitted to a USB enabled microcontroller.