Identify is a Firefox extension by Glenn Jones that uses the Google Social Graph API to identify people based on the
rel="me" link attribute. It’s easy to use—“Ctrl + I” (Mac) or “Alt + I” (Windows) on someone’s Twitter profile, for example—it pulls in available data from the present site and other social web sites. According to Google’s API, the plugin can identify public URLs that belong to the person being looked up, and publicly declared connections between that person and others. The plugin gives a sense of how quickly one can be identified when software aggregates information spread across multiple applications. So, you know, be careful.
Via Marshall Kirkpatrick.