Pachube
Pachube is a technically oriented website for sharing data streams from realtime sensors, such as environmental monitors (temperature, humidity, etc), or any other internet connected data source.
You can publish your own data streams to Pachube using their API, and you can search or brows for data streams that other people are providing.
The Pachube website lets you create live graphs of data streams from public devices, and embed them in websites.
Developers can use data shared on Pachube in their applications and Pachube can be configured to notify your application when certain conditions are met.