Falun Dafa (also known as Falun Gong) is a form of ancient qigong, the practice of refining the body, mind and soul using special exercises and meditation. It is very much in the ritual families of related activities like tai chi. Falun Dafa/Gong is a modern interpretation of qigong that was introduced to the public in China in 1992 by one Mr. Li Hongzhi.
The cruxes of Falun Dafa are studying Mr. Li's teachings and performing Falun Dafa five "gentle exercises". The teaching are found in the books Falun Gong (Law Wheel Qigong) and Zhuan Falun (Turning the Law Wheel).
The official web site of Falun Dafa is (if you can't guess) falundafa.org, and there are many regional Dafa groups in over 40 countries world-wide. In my area, Salt Lake City, the Mayor (Rocky Anderson) has declared January 22-28 as "Falun Dafa Week (http://www25.brinkster.com/falunut/award.jpg).
Of course, not everyone is brimming with love toward Falun Dafa; many see it as a 'cult' system. As one noder eloquently put it:
<achan-love> falun dafa can kiss my ass
<achan-love> and then they can meditate on it
But I'm sure he meant it as a joke. I think.