If I was going to hang a large print on my walls I wouldn’t go for some art piece or a photo (although I do like to dabble in photography from time to time), no what I’d probably go for is a giant print of our galaxy or one of our close neighbours. Even better would be something that was interactive as I’ve always enjoyed programs like Celestia that let you zoom around the galaxy, checking out all the billions stars and (just recently) their orbiting planets.
It seems some of the guys at Microsoft have a similar appreciation:http://www.youtube.com/watch?v=YzoXPav7uzs
The Microsoft Surface has always been an amazing piece of kit and it never fails to surprise me when they bring out yet another innovative idea based around it. Whilst I can’t really think of any kind of practical use for something like this I do think it would be awesome as a tool to get people interested in space (kids especially).