I was walking in the mall the other day and I passed by the aliant (telephone comp.) store. They have glass from floor to ceiling on the sides and they somehow project ads onto the glass.
I finally figured out how they do it! They have a projector on the ceiling inside the store and thay project onto a mirror and that image projects onto the glass! The coolest thing is is that the light from the image does not shine through the glass!
I thought this would be a cool idea for a HTPC or for a hideaway display. Just wanted to share this because I think it's pretty cool!