Saw a post from last night/weekend about the Concorde and I ended up "wasting" a lot of time today reading about it on Wikipedia. It was a seriously amazing plane and beautiful in person. I was fortunate enough to see it a couple times, though never in flight. Even sitting on the ground it looked fast and graceful.
It is one of the most interesting planes ever IMO and pioneered some pretty cool technology. It was the first to use carbon brakes, and I can see why they did. The carbon brakes saved ~12,000 lbs over using conventional steel brakes for Concorde.