The library supports more than 70 sites, including all the popular ones like Twitter, Flickr, Facebook or Youtube.
From Glenn Jones, the creator of the library:
Wouldn’t it be a little magical if, when you signed up for a new site, the site said something like, “We notice you have a profile photo on Flickr and Twitter, would you like to use one of those or upload a new one?”
Ident Engine makes this totally possible.
It analyzes the relations between various networks using the
rel="me" tags & Social Graph API’s "lookup" method.