At the UK Vista and Office 2007 developer launchh event a few weeks back, I had Rich Griffin from Conchango come on stage to give a sneak preview of the Daily Mail eReader he was working on a few months back. You can still watch or download the video online
(It looks even better on 1920x1200 resolution)
The Daily Mail eReader has now launched in Beta form and I think it is a great application that shows off what you can do with WPF. The New York Times reader is a great example of what you can do with document services in WPF but it's always nice to have a local version to show off (even if it is a bit more tabloid than broadsheet ;-)).
The cool things for me in this app are: