You probably think that Tai Chi is a slow, gentle form of exercise for old people and new agers. But in fact, what most people have seen is extremely watered down and whimpy. The real Tai Chi is a fast, deadly, forceful martial art. But almost nobody teaches it that way in the West.
However, my brother, Marin Spivack, does. He speaks fluent Chinese and went to China to seek out and study with some of the greatest living teachers, for many years. Now he's one of the few people teaching the real deal in the USA (in the Boston area). Check out these videos of him showing the form and then toppling various people who outweigh him. They're beautiful and impressive.
This first video is really cool -- make sure to watch all the way through. Towards the end he starts doing some of the more intense fighting moves, which you've probably never seen before.
Next, here's a video of Marin demonstrating grappling techniques with a guy who is not only much taller but probably 3 times his weight and strength:
The next two clips show some various fighting techniques...