Instructables user hanlin_y did the math and realized that alkaline batteries are one of the most expensive forms of power that consumers can use. So he/she/it came up with a solution to power your parts even if they don't come with an AC adapter. With a wall plug, wires, and bamboo strips you can run your electronics off the grid; saving money and the environment at the same time.
Czech glass artist Michal Zahradnik> designed this all-glass steam engine, which he claims is fully operational and can run at 500rpm. Some of his other creations include a model plane and Harley-style motorcycle. All I know is the sound this thing makes is going to haunt my dreams.
Zapata Racing just released the Flyboard, a water-powered jet pack available to the public. The Flyboard gets it propulsion from a jet ski idling nearby; its hose forces water to shoot out of the user's feet. Not as cool as a the real deal the public is waiting on, but I guess this is a happy medium for now.