Three Varieties of Creationist.

Hopefully as readers of my blog you may have often noticed, several of my post tend to mention or criticise creationists and creationism. Nevertheless, I should perhaps make it a little more precise to exactly what “I” mean by the term "creationist", because there is an assortment of types and, predictably, they don't all have the same opinion with one another.
This obviously can make it very tricky when attempting to deal with someone who begins denying evolution, or a discussion about Noah and the Flood or the old (or new depending how you look at it) age of the universe. Seldom will they actually say "I'm a young-earth creationist", and may even take some offence if you attach such a label to them. Nonetheless, once you have a vague idea of the key things that they accept as true, many other of their beliefs will then slot into place. This can give you an excellent idea of where they are coming from as people, but you must still be very vigilant about making too many assumptions about them. There are many different varieties of creationists and creationism, and individual advocates to each branch will have their own set of “facts” about the matter.

Young Earth Creationist (YEC)
These appear to be the most widespread sort, or at least the most vocal, at least in the talk boards and debate forums I know. The YEC is often, but not always, an American fundamentalist Christian (or is influenced by such people. I point out this is my experience and not a general snapshot of all creationist debate board users) and tends to believe in some or all of the following:
The Book Of Genesis (and often the entire Bible) should be read as literally as possible.
Strong objection to evolution (both the fact and the theory), usually accompanied by a substantial misunderstanding (or plain ignorance) of the subject.
God created the universe in seven days, less than 10,000 years ago (hence the name "Young Earth"). Adam and Eve lived in the Garden of Eden, and were cast out (the Fall).
The world was indeed flooded (the Noachian Deluge), and all present land-life is directly descended from Noah's family and the various "kinds" of creatures on the Ark. Some YECs use microevolution to explain how the millions of species we observe today formed from the initial "kinds" (even though that requires evolution to work at a fantastically accelerated rate), but do not accept that macroevolution occurs at all (even though it is essentially the same thing, over a longer period of time).
Noah's Ark is still to be seen on top of Mt.Ararat. (Several expeditions have attempted to find it, but the political situation in Turkey at the moment makes it difficult to get permission, otherwise it would certainly be an annual event.)
The light from distant stars (more than 10,000 light years away) was created in situ by God, to give the misleading appearance of great age (similar arguments are applied to many similar problems, such as the dating of rocks and fossils).
Fossils are evidence of the Flood, as they were all formed from the bodies of animals that drowned during the Flood.
Humans were special Creations of God, and we are most certainly not related to monkeys of any sort (being conjured up from mud seems much more acceptable, strangely).
The scientific method is an extremely poor way to discover the truth about the universe, and God's obvious presence should be the basis of all inquiry. Any evidence that appears to disagree with the Biblical account should be called into question, if not dismissed altogether. The Bible may be considered to be a useful (or even definitive) science textbook.
The answers to most of lifes problems can be found by reading Genesis correctly. Only by first learning about God may we learn about the universe He created.
Evolution (which does not happen) is thought to be an entirely random process.
Evolution is "only a theory", and therefore should not be considered factual. "Theory" to a creationism means the same as a "wild guess" in this context. Creationism should be taught in science classes alongside, or preferably instead of, the theory of evolution.
The theory of evolution is the cause of many of society's problems (such as racism, eugenics, drugs, immorality and so on).
A minority of YECs seem to think that there is a global conspiracy among scientists, atheists, NASA and the government to conceal the Truth (i.e. that the Earth is young, the Bible is true and evolution is a myth).
Evolutionism is a religion (and should not be forced upon schoolchildren); creationism is a science (and should be taught to schoolchildren as such).

Old Earth Creationist (OEC)
OECs are a great deal more liberal than YECs in their philosophy, and also more diverse. They tend to acknowledge many more of the findings of science, especially to do with the age of the universe (at present estimated at 14.55 billion years), even though there is likely to be some overlap with YEC beliefs. The bulk of theists would most likely loosely fit the explanation of an OEC, although they probably wouldn't identify themselves as such. Their beliefs tend to include:
The Earth and universe are indeed ancient. However, God still created it all, but over a period of many years (the seven "days" become seven long periods). Alternatively, God caused the Big Bang in such a way as to ensure that the Earth formed as we see it today.
The scientific method is a good way to discover the truth about the universe, but God's presence should not be lightly dismissed. Any evidence that appears to disagree with the Biblical account should be examined carefully, but tentatively accepted if it stands up to scrutiny. The Bible may be an excellent guide to life, but it is not a science book. By learning about the universe we may learn something of God.
The description of Creation in Genesis may be seen to match the scientific explanation of the origins of the universe and life on Earth. e.g. "Let there be light" corresponds to the Big Bang, and the sequence of events when God created life roughly correspond to the sequence described by the theory of evolution.
Some OECs accept that humans evolved, but believe God was in control all (or at least some of) the time (this is also known as "theistic" or "guided" evolution). God uses evolution as a tool to direct the development of life.
Alternatively, all other life evolved as normal, but God created humans himself, or created us by adding a soul to our soul-less ancestors when they had reached to appropriate stage of development (this appears to be the official position of the Roman Catholic Church, for instance).
Some OECs still do not accept evolution, but feel that God creates new species Himself, either when current ones naturally die out or just when the time is right. In His mysterious manner, God inexplicably creates things in such a way as to give the impression (to the uninformed) that they evolved. But they didn't.

Intelligent Designer (ID)
IDs are little more than modern version of YECs.
Some YECs, realising that they were getting nowhere in their challenge to replace evolution with creationism in school science classes, are now instead trying to introduce the theory of "Intelligent Design". This is on the whole creationism stripped of all religious references – no Genesis, no Jesus, no Noah, no Bible, no God. The idea is pretty much the same, however. The universe is so astoundingly intricate that it just had to have been designed by a powerful intelligence. It amounts to the Argument from Design wearing the Emperor's New Clothes, nothing has changed but the way it is described, and seems to be a very persuasive and insidious (as well as scheming and cynical) way of getting creationism accepted by school boards and parents.
The argument from "irreducible complexity" is one of the main weapons used. The idea here is that if something cannot possibly function with any of its parts missing, then it is irreducibly complex, and cannot possibly have come to be without some sort of outside intelligence causing its design. Complex biochemical processes in the human body are favourite examples. They believe that if something is so complex that it cannot possibly have formed through natural processes (such as evolution) then the only option available is an intelligent designer - e.g. a supernatural being - e.g. a deity - e.g. the Christian God of the Bible. In the dichotomy they wish to establish, if there is no possible natural cause, then the cause must be supernatural.
It is obviously a very short step from saying that there is an Intelligent Designer to saying "And just who could that Designer be? Why, pick up your Bibles and find out!".
In a Christian-dominated country such as the USA, having Intelligent Design introduced into schools as a respectable science is effectively the same as replacing science with fundamentalist Biblical Creationism. If children are being taught about God as The Creator at home and in church, and their science teachers start talking about an Intelligent Powerful Force That Created The Universe, it's quite obvious that the children will see them as being one and the same. Call me an old cynic, but that is clearly the agenda here.
The IDs try to distance themselves from "traditional" creationists, as they wish to be seen as serious scientists trying to enlighten us and not Christian Fundamentalists trying to preach to us. Rather than relying on anecdotal evidence of miracles, they want to present a convincing, scientific case for Intelligent Design (creation) – or at least cast enough doubt on mainstream science that people will see their theories as a reasonable alternative.
To a certain extent, this is just a new version of the God Of The Gaps idea – things that science currently has trouble explaining are viewed as being inexplicable except through a superhuman Intelligent Designer (God). Of course, if everyone were to subscribe to this, then all science would come to a screeching halt ("You can't work out that problem? Then don't think about it any further – God did it.").
( Presumably, the examples of duff design to be found throughout nature are due to the Intelligent Designer trying to throw us off the scent… )
OECs and YECs tend to strongly disagree with each other, and you can probably find many websites from each side that attack the opposing point of view (oh, the bitter irony).