Wikis

To get a good definition of a wiki, I went to the wikipedia site:

A wiki is a website that allows visitors to add, remove, edit and change content, typically without the need for registration. It also allows for linking among any number of pages. This ease of interaction and operation makes a wiki an effective tool for mass collaborative authoring.

pbWiki is a site that allows you "make a free wiki as easy as a peanut butter sandwich". Wikis are fun for setting up collaborative projects such as shared story writing. You can control the access to the wiki with passwords.