This page shows different sensors I have interfaced to upload their data directly on the internet.

Temperature and Humidity
Gets data from an Arduino Yún and uploads them
directly on the internet with the bridge library and cURL.
(Updates ~ 5 seconds)
http://pascalnet.net/misc/dht22/

Voltage
Data sent from a digital multimeter via
an optical serial port and sent on the internet
with a C# program running on a netbook.
(Updates ~ 5 seconds)
http://pascalnet.net/misc/multimeter/

Radioactivity in Montreal, Quebec, Canada
Arduino compatible geiger counter sends
data via serial port and on the internet
with a C# program running on a netbook.
(Updates ~ 1 minute)
http://pascalnet.net/misc/geiger/