Please see the most recent updates in the "Where did the .com name go?" thread. Posts number 16 and 17.
Aurora....

X43A,, mach 10
imagine if it were upscaled and crewed!!North American X-15 4,520mph and crewed.
I believe the Russians built an interceptor that was capable of higher speeds than the Blackbird, but only in a sprint, and then it had to be retired due to airframe stress.
So noone got my shameless hacking of this thread to give away a spoiler?