Wikis are website that allow any user to update and edit the information they contain. The biggest and best known wiki is Wikipedia, an ambitious free web-based encyclopedia project with over 1.2 billion articles in English.
Of interest to HIA practtioners are the HIA Wiki, which was started by Salim Vohra, and the HIA page on Wikipedia. You can use these not only as a source information but also as a vehicle for updating others on HIA-related developments.
A number of people have expressed concerns about wikis' unmoderated nature. I think that when using a wiki it's important to view the page history to assess if what you're reading is the result of informed and constructive contributions. The other thing to keep in mind is that even with traditional mediums such as books and journals the editorial and peer-review processes aren't rock-solid guarantees of quality. Critical appraisal has always been important.
Please take a look at both wikis. I'd be interested in your impressions of them.