http://en.wikipedia.org/wiki/William_BranhamHere is a somewhat concise article in Wikipedia about Branham. His theology was a bit odd...while he preached Oneness, he later said that both Oneness (as many Pentecostals taught it) and Trinity were wrong. I am not sure how Branham came up with that conclusion. He was at one time a Jesus' name preacher who was popular with the faith healing crowds throughout the 1940s and 1950s. My former pastor's father was baptized in Jesus' name following one of Branham's revivals, and was a well-known Oneness preacher in Lancaster, Pennsylania until God took him home in 2005 (he was not a Branhamite).
I would venture to say that William Branham at one time walked in truth, but due to in part his own lack of education and poor choice of associates, he started messing with strange doctrines such as the infamous "serpent seed". Somehow, because Branham continued to go further into the deep end, God allowed a drunk driver to take him out of the picture in 1965.
The link given by the other contributor was indeed a link to Gary Reckhart.