When I was in college one of my favorite movies was Star Trek IV.  My then-girlfriend Patty and I must have seen it (at the theatre) like 8 times.  In STIV the crew goes back in time to Earth of the past. Once there Mr. Scott must build a tank big enough to hold a pair of humpback whales aboard a spacecraft, and he remarks that the best material for the job would be transparent aluminum.  Later he trades the formula for transparent aluminum with the owner of a plexiglass factory for the materials he needs to build a whale tank.

Well apparently, transparent aluminum is no longer science fiction: Air Force testing new transparent armor.

Thanks to SlashDot for the link.