This is pretty cool. Some "professional Lego builders" have made a half-size scale model of a Rolls-Royce Trent 1000 jet engine, and it goes round! It was inspired by a model made by a 5-year-old boy and his dad.
Allegedly, it's made from only standard Lego bricks. I'd love to take it apart to see how they did it.
The Trent 1000 powers the Boeing Dreamliner.