Here is a sampling of links to websites representing a variety of forms of creationism, including Young Earth, Old Earth, and Intelligent Design creationism.
Access Research Network
Promoters of "Intelligent Design" Creationism.
Creation Research Society
Another creationist organization.
Center for Science and Culture (Discovery Institute)
The "intelligent design" think tank associated with the Seattle-based Discovery Institute.
Christian Answers
A Christian site with a lot of links to other creationist sites.
The Creation Research Society
The "research arm" of the creation science movement. Young-earth creationist articles are published in the journal CRS Quarterly
Reasons to Believe
A Christian ministry that favors the "old Earth" view: ancient age of the universe and Earth is accepted, but not biological evolution.
Institute for Creation Research
A major center of young-earth creationism.
Answers in Genesis
Young-earth creationist ministry,
International Society for Complexity, Information, and Design(ISCID)
A new organization advocating "Intelligent Design Creationism," headed by William Dembski.
Science Excellence for All Ohioans (SEAO)
An "Intelligent Design Creationism" organization in Ohio, actively promoting the watering down of evolution in Ohio's state science standards.
See also this list of creationist web sites maintained by the Talk.Origins Archive (not itself a creationist web site).
Talk.origins's list of creationist web sites