Supported by Jerome Foundation
PuréeData is a web-browser interface for a single shared sound environment that allows live, collaborative patching for anyone, anywhere. Visitors interact with a shared PureData audio synthesis patch and listen to the results as an MP3 stream, with no software to install or set up. The project is open-source, and all are encouraged to modify, improve and set up their own PuréeData servers.
The interface http://pureedata.net is not working at this time, but you can access and/or fork the code at Github.