Wiki Wiki means quick in Hawian (apparently). Wiki systems allow you to edit web pages in a browser. Pages are linked by the use of CapitalisedRunTogetherWords - when you put one of these in the text of the page it creates an automatic link to a new page where you can write about "Capitalised Run Together Words" or whatever.
The result is that you can create pages quickly and easily, on your own or in collaboration with others.
I use the TWiki implementation of Wiki Wiki.
See also: Wiki Wiki Fever, the original Wiki at http://www.c2.org
-- Andy Pryke - 23 Feb 2002