The most expensive sharing thing I've found so far is JetSmarter. An app for flying private jets all over the world. In March and April they will start with free shuttle flights in Europe. The idea is that many private jets fly empty legs to get to destinations where someone is going to fly from. And so they can take other passengers on these legs. The jet owner can share it with other people, so it's a way of using the resource more efficiently, similar to car sharing or renting. And flying for free sounds great. There's only one catch: you have to purchase a membership for 7000 dollars. Hmm... that is slightly out of my budget... Too bad, it would be such a cool thing to try!