Another app that's currently using XML is jabber, which is basically an IM, although if I'm not mistaken a few companies are looking at using it for a lot more than that. Jabber sends messages as XML data. www.jabber.org. Here's a link to a Dr. Dobbs interview about jabber: http://www.technetcast.com/tnc_play_stream.html?stream_id=384 A lot of apps are using XML in some way or another, although most of them don't currently use DTDs. Most of them just use the XML data structure.