Above are two video clips of RC ornithopters in flight. An ornithopter is a flying machine that flaps its wings like a bird.
The first video is of an older model, the Park Hawk from 1993. It gives a good view of the mechanism to flap the wings as well as the control surfaces in the tail. Plus the views of it in flight are pretty amazing in how much it behaves like a bird.
The second video uses a technique dear to my heart, namely strapping a mini-camera onto a couple of other ornithopter models so we can get a mechanical bird's eye view of the flight. One thing that is obvious is the body bounces up and down a considerable amount while it is in flight. My advice -- if they ever form ornithopter-based commercial airlines buy as much stock in companies that sell airline sickness bags as you can afford.
Of course, with the models already built there are now people working on human powered ornithopters. The website Ornithopter Zone has a section, Manned Ornithopter Flights, that detail the history of these efforts. The upshot is that while a lot of people have claimed human-powered ornithopter flight, none of their claims are all that convincing. The problem is that they use some means of getting up to take-off speed -- most commonly via tow ropes -- and it then becomes difficult to assess if they've perfomed any better than a glider would.
Below is a video of one such flight, by James DeLaurier and a team from the University of Toronto Institute for Aerospace Studies, that is assisted by jets for take-off. It sort of gets off the ground, but doesn't end well.