If you're looking for samples of all the good stuff you can do with WPF, then go no further than the official MS WPF WIki's list: Application Portfolio.
- Kordesy's favourite: OTTO - Online clothing shopping (APPLICATION). hmm...
- My favourite: DominoKen - Artistic 3D XBAP demonstration from Microsoft Japan (XBAP).
Well at least Kordesy's has a purpose I guess.
Also, keep an eye on Tim Sneath's blog, for his series on Great WPF Applcations.
And finally, haven't managed to get the stuff from our own Mobilewares in Melbourne on the list yet - but check them out too for some good examples of WPF on Media Centre.