First of all, what is a WIKI?, well lets go to the WIKIPEDIA definition of WIKI:

A wiki is a website that uses wiki software, allowing the easy creation and editing of any number of interlinked Web pages, using a simple text editor, within the browser. Wikis are often used to create collaborative websites, to power community websites, and for note taking. The collaborative encyclopedia Wikipedia is one of the best-known wikis. Wikis are used in business to provide intranet and knowledge management systems.
Source: http://en.wikipedia.org/wiki/WIKI

A wiki could be use for collaborative projects, events and more. In business all this is going to be published online so you could use it to promote your events and products by creating a wiki about them and having the members of these events or product collaborate. Remember to create links back to your blog (were you talk about the event) or to your website, were you have information about yout product.

Here is a good video about how wikis work and how you can create one.

Destiny.