Rolling a 747
One paragraph of this ode to the 747 blew me away: “Even then, and despite the 747′s formidable technical specification, it has always seemed a wonder that such a massive machine can actually get off the ground, let alone fly so fast – the plane cruises at Mach 0.85-0.88, not far below the speed of sound – and so very well. No one knows if a 747 will barrel-roll or loop-the-loop because no pilot has been mad enough to try. Boeing engineers think both manoeuvres might be possible, although 400 passengers tucking in to chicken-or-fish and red-or-white wine might never forgive a pilot willing to have a go.”
A barrel-roll? WTF? Anyway, I poked around a bit more and it sounds like it’d be possible, though as The Straight Dope points out, “The problem is not so much with the strength of the wings, which are designed to stand much greater pressures, as with the skill of the pilot.” Oh, and some guy actually rolled a 707 in a display flight.

Hi, I'm 
just had to thank you for reminding of The Straight Dope. Had a dog-eared copy throughout adolescence. well done.
Say barrel roll again:
http://www.youtube.com/watch?v=wIkJvY96i8w
:)
This may be fake and I’m too lazy to look it up, but I heard that you can take a 747′s wings and bend them up to touch each other. That in itself is amazing. Also, speaking of pilot’s “trying things”, I seem to remember some FedEx (or UPS) pilots who decided to test the max altitude their jet could do. Didn’t work out so well.
I too am amazed every time I see a huge jet take off, and despite my understanding of the bernoulli equation (a weak understanding at that) it still seems like magic to me.
Someone else in Stockholm thought to do something a little different with a 747… check it