Flat-Earth Geocentrism-is perhaps the most extreme form of Old Testament Literalism. Because of
specific passages in the Bible or Quron, these individuals claim the planet is flat and the center of the solar system and universe. Very popular in Islamic Nations and has a few followers here in the US as well.
Geocentrism-accepts that the earth is spherical, but maintain it must be the center of the solar system, again because of passages in the Old Testament. The greatest proponent is
DR Geradous Bouw, who incidentally holds a flippin Ph. D. in astronomy. Both flat earthers and geocentrists are convinced the Apollo Moon Landing's were faked by NASA. (A few years ago, Apollo 11 Astronaut Buzz Aldrin finally
punched out a guy who'd been stalking him for years, claiming the moon landings were fake, and harassing Buzz to swear on a Bible that he really did land there)
Hollow Earth Creationism-is a sort of weird subset of flat earthism. These clowns claim we live on the inside of a hollow earth, or they claim the earth is hollow, and the Lost tribes of Israel and some kind of Kingdom of God lays inside the planet. And if you think I'm making this up, recently, an expedition was organized to reach this inner land, usually called Pellucidar, and you could have bought a ticket, for a most reasonable fee ... Although success was not of course, guaranteed.
Young Earth Creationism-is by far the most common type of creationism prevalent in the grass roots fundamentalist public of the US and Europe today. YECists accept that the earth is round and orbits the sun, however they reject evolution, they claim the earth and the universe are less than 10,000 years old, and they advocate that all geological and fossil evidence is the result of a Noachian Flood. See the IRC, AiG.
Old Earth Creationism-is split on the Noachian Flood event, some accept it and some do not. They tend to accept the age of the earth and the universe. But reject common descent/evolution. Hugh Ross of Reasons to Believe, is perhaps the most notable and most credible OECist in the US.
A notable form of Old Earth Creationism is the Islamic version, promoted by Turkish author and businessman Odnan Oktar and others under the pseudonym Harun Yayha. Folks, you cannot call yourself a creationist debater, until you have gotten into a discussion on science with a victim of Harun Yayha's. It's about as productive as smashing your brain pan out with a cinder block.
Intelligent Design Creationism as a Political Movement-are composed of any and all the above. The official position goes something like "At some point in the past, a designer of an unknown type (cough God/YVWH cough), may have intelligently designed some 'stuff', for reasons we can't possibly know, using methods we can't possibly know, except we do know He Did Not Use Evolution!"
IDC seeks to act as a big tent type of political front. When in front of intelligent audiences, they stress the Old Earth Variety, when in front of secular audiences they claim it's a purely scientific theory and has nothing to do with Biblical Creationism, and when in front of their fundamentalist bread and butter groups, they either avoid the topic of age altogether, or imply the YECists could be right, and openly state it's all about God and fundamentalist hatred of science. The leading political organization, and the current Flagship of anti-science idiocy in America, is the Discovery Institute Center for Science and Culture (Catchy name huh?). These are the guys to know if you're going to be fighting this crazy shit: Phil Johnson,William Dembski and Michael Behe, or Stephen Meyer and Jonathan Wells, are good places to get quickly acquainted with these assholes.
IMPORTANT NOTE: Every other group on this page, in itself, is relatively harmless. These clowns at the Discovery Institute are not harmless at all. They're an umbrella for all the other groups, acting as a coordinated PR front and weilding significant political and financial support. They plan to first challenge evolution, and then using that model, destroy all of science, and replace it with theistically approved 'science'. Recently the Vice-President of the Discovery Institute mangled General Relatiivity and Big Bang Cosmology, while ridiculing/distorting Einstien. Their goal is Science by Fatwa, and I'm sure you can guess which religion they plan on using to issue the Fatwas. Lastly, pretty much everyone of these anti-science liars and most of their victims are staunch social conservative and devout supporters of George W. Bush. So if you wonder why so many scientists are running away from the Republican Party screaming in horror, now you know.
Update: Pigpaste correctly points out in comments I should have left a link explaining the Wedge document, the DI's master strategy to destroy science.
Intelligent Design as a research topic-is a legitimate field of inquiry, although the IDCists have pretty much ruined it for everyone by associating it with duplicity and medieval fundamentalism. The legit techniques are used by orgs such as the NSA to recognize coded messages, or by SETI Researchers in trying to detect extraterrestrial intelligence.
In addition there are forms of creationism which don't fit so neatly into the above hierarchy.
Scientology Creationism-is too bizarre to try and explain. It basically says humans evolved from clams over 60 trillion years, and were once both birds and sloths.
Raelian Creationism-Raelians Worship a mythological alien, which in their literature looks like a typical X-Files kind of "Gray". They believe the grays created mankind using cloning techniques, and will soon return to earth.
There are a lot of weird quasi-offshoots of Raelianism. Perhaps the best known is the Heaven's Gate group which committed suicide in mass, believing that by doing so ... they would join the alien mothership traveling undetected (Dare I say 'cloaked'?) inside the coma of the Hale-Bopp Comet.
Hindu Creationism-is little followed in the US and the West. Perhaps best known for the series called Forbidden Archeology by Micheal Cremo and Richard Thompson. It is very popular in India however, where Hindu Fundamentalist have recently swept into power much like their Neo-Christian counterparts here in the United States.
Resources for fighting Creationism.
Talk Origins Archive, probably the most extensive website on the planet with enough links to keep you busy for months. Pretty much every creationist argument you can imagine is refuted here by a qualified scientist in the field.
Bob's Site-one of the most extensive collections of high quality articles and graphics in America. Wonderful drill down and well maintained.
Update: Commentator Freelunch added the National Center for Science Education, run by my co-creationist fighters the brilliant Eugenie Scott and Wesley Elsberry, among others. And the Understanding Evolution website. Both excellent resources.
Evo Vs Creationism Blogs: The Panda's Thumb, Pharyngula,Dispatches From The Culture Wars, Thoughts From Kansas, De Rerum Natura, and my own modest efforts can be found from time to time at Unscrewing the Inscrutable.
Message Boards: Evolution Vs Creationism Community, Talk Origins Newsgroup.
Anyone is welcome to e-mail me at anytime on this issue at Darksydothemoon@Ao'hell'-dot-com.
Next week, time permitting, I hope to start another week long science series called The Greatest True Story Ever Told, which starts with the Big Bang, and goes through to modern times, hitting a few highlights along the way. Hope you enjoy!