Here's one that's been building up for a while. Elon Musk had announced that he would release the open source designs of the Hyperloop on Monday and now we can see what it might look like.
The Hyperloop was originally described as a cross between concorde, a railgun and a hockey table, and could potentially take passengers half way around the world in 6 hours. Creator Elon Musk chose to make the designs open source to encourage engineers and designers to come up with creative solutions and applications for the Hyperloop.
The Hyperloop works by sending capsules through a near vacuum in a tube, levetating in a magnetic field at speeds of 800mph. Automated airlocks could load and send off new carriages every 30 seconds and the passengers would feel less force than when an airplane takes off. When the capsule reaches its destination the energy from the brakes would be used to power the next departure, and solar panels on top of the tubes would generate more energy than the system uses.
The first demo version would run between LA and San Fransico, but the potential applications could run much further, faster and significantly cheaper than other high speed rail plans. Plus the Hyperloop could be built underwater.