A Century of Pentecostalism
It all began with the Azusa Street Revival in Los Angeles: Pentecostalism at 100: a major religious force.

The article notes that largest church in the world is Pentecostal:

South Korea's Yoido Full Gospel Church, begun in a tent in a Seoul slum in 1958, boasts more than 700,000 members.

The movement's influence on (infiltration into?) Catholicism in the form of the Charismatic Movement is also mentioned in the article, as are its assault on traditional music and its "prosperity gospel." Not mentioned in the article is the interesting fact that the movement was begun by Blacks, quickly joined by Whites and integrated, and then later segregated.