hyperstruct blog Exchanging Data Between Chrome and Content
http://blog.hyperstruct.net/2006/08/18/exchanging-data-between-chrome-and-content
"Scenario: a chrome and a content application are aware of their respective existence and wish to communicate. Communication should be able to flow both ways."
DocDescriptionRemoteApplications - xmpp4moz - Trac
http://dev.hyperstruct.net/xmpp4moz/wiki/DocDescriptionRemoteApplications
"Example: notetaking application"