Other than Scientology, the more famous alternatives are the Raëlian Movement, Heaven’s Gate cult (extinct), and the Nation of Islam. These are all religions with some belief in extraterrestrial origins. A complete list can be found here.
But apparently it isn’t necessary to have a religion to believe in extraterrestrial origins. That would also explain the high response rate on the poll for the option “Humans were brought to Earth from the stars”. The majority (I think) are agnostic people who believe this as there are many authors still writing today on the evidence (as they see it) for E.T. origins but are not promoting a (named) religion.
If we concentrate on the earliest records of these ideas, we see that there is a common thread; Scientology, Raëlism and other non-religious theories all started in the late '60s and early '70s. This was a time - you will all recall, I’m sure 
- of the rise of the Sci-Fi genre; The Twilight Zone, The Day of the Triffids, 2001: A Space Odyssey, Planet of the Apes, Star Trek, Star Wars, and so on. These ideas were prevalent at a time when man ventured further into space and the questions of “What if we met these aliens?” started to become popular. It is not surprising that after the sensory bombardments of these strange new people, new worlds and new ideas (in TechniColor!) that many would try to reconcile the imaginary world of aliens with the real world. I’ll concentrate on listing the earliest writings about E.T. origins …
Extraterrestrial Origins
- Operating Thetan level III (OT III) - L. Ron Hubbard (1967). Not the start of Scientology, but the incorporation of E.T. origins.
- Chariots of the Gods?: Unsolved Mysteries of the Past - Erich von Däniken (1968)
- God Drives a Flying Saucer - R. L. Dione (1969)
- The Book Which Tells the Truth - Claude Vorilhon (1974). This book was the founding of the church of Raël.
- Our Ancestors Came from Outer Space - Maurice Chatelain (1975)
But not only did new religions like Raëlism and Scientology start then, but a more familiar one started to get some revisioning…
Christianity
- The Bible and Flying Saucers - Rev. Dr. Barry H. Downing (1968)
- The Moon: Key to the Bible - Jean Sendy (1968)
- The Spaceships of Ezekiel - Josef Blumrich (1973)
A more complete list of recent writings can be found here in the Extraterrestrial Origins Library.
The majority of the writings, which use the bible as evidence, analyse the passage relating Ezekiel’s vision of god descending from heaven (that whole “wheels within wheels” chestnut). An excellent analysis of this interpretation of the passage can be found on Michael Shermer’s Skeptic Magazine website.
As an asside, it is interesting to note that it is not only the Scientologists who have their sights set on Africa, the Raëlians have also recently begun activity on our continent.