Transparent PCs (kind of...) on flickr
Check out this flickr search: http://www.flickr.com/photos/tags/transparent/ and this photo pool:
It will show you (mostly) a series of photographs of "transparent" PCs. A sort of tromp d'oleil where you use a photo of what's behind your PC as your desktop wallpaper. The result:
A seriously convincing and clever looking set-up. This reminds me of the "invisible coat" developed by some scientists over in Japan. In essence, it was a jacket that reflected a projected image from a live feed camera positioned directly behind the subject. Yes, not really too high tech in this form, but in the future nanocameras and nanodisplays would make this more usable.