If you're interested ion the Internet of Things you probably know about Pachube. They offer a free real-time data infrastructure that makes it easy for users to share data from just about any internet-enabled device.
Through the Pachube website you can monitor the temperature in Iceland, the humidity in London or the radiation in Japan. You can even set up triggers so that you get an SMS alert whenever a value exceeds a specified threshold.
Pachube are currently organising a series of Data Making Workshops to help people get started with their service. I've just got back from one; it was great fun and really informative. About a dozen of us worked our way through Pachube's API, and then set up data feeds from our ethernet-enabled Arduinos. (If you're curious about the light level in my study at home, you're welcome to take a look.)
It was a great practical introduction, and gave us lots of ideas for future projects.
Pachube will be organising more introductory and advanced workshops in London, Barcelona and New York. Details on their website. If you're based in London, you can enrol via this meetup.
The current API is great but there are some interesting beta interfaces available to the brave and curious. There's a web-socket implementation as well as an mqtt bridge. Because they are betas, both services are subject the the usual caveats: the API might change dramatically, and the service might be withdrawn. That said, these are services that are likely to be of long-term significance, and it's great to have a chance to try them out.
And now I'm off to write a Python wrapper for their API; it should be useful for the Beaglebone, Beagleboard and Raspberry Pi.