A relatively new web service called GroveStreams allows you to upload sensor data (or any other data) to the web for display and analysis. The have a sample tutorial for the Arduino which simulates a periodic temperature reading. This displays as a graph and or as a dashboard with a variety of beautifully rendered sample gauges.
I found the site when looking for Pachube, a frequently-mentioned similar service which appears to have morphed into a service called Xively offered by the LogMeIn folks. While Xively offers a free developer’s account, if you begin to use it commercially, the cost is $999/year plus transactions costs based on volume of data and number of streams. GroveStream also has paid accounts but the threshold for payment comes somewhat higher, allowing us small guys to experiment.
The GroveStream Arduino tutorial requires an Arduino with network connectivity. A Uno works fine, and I don’t think there would a problem with the predecessor Duemilanove. I had a Seeedstudio Ethernet shield lying around which worked well, and I was able to send data to the GroveStream about 30 minutes after starting the project.
Comments in the Arduino sketch reference a web site by David Thompson, which has a enormous trove of examples, code, and experience for Arduino-based home automation as well as a newer revised version of his home automation controller based on the Raspberry Pi.