First off, you can write your own wiki page, using PHP/MySQL or any other scripting language/database. You can also write a wiki module for content management systems such as Wordpress. There are also off the shelf and -- best of all -- open source packages that should be more than adequate for your needs. If you are a developer and you need a flexible tool to build wiki pages, but you have no budget and limited time, open source projects on Source Forge will be more than adequate.
There are also tools for non-developers. Some work with advertisements, but all in all they work excellently. One is PB wiki; it's free, but charges for extra options. Another is wet paint; it's also free, but comes with advertisements. JotSpot is going to be a big contender soon, once they start accepting new members. If you are creating a for-profit wiki site, an open source project or hiring a developer may be the best way for you to go, so as to avoid branding other peoples products for free on your web site. On the other hand, as Wordpress has proved, you can use free software successfully on commercial sites. Another powerful tool is Nexus which was created by start up software firm Mindtouch; alas, it is not free.
Why Wiki?
Why should a web site utilize a wiki approach? I say it should be done for content and for money. It should be done for content because turning the site over to users ensures timeliness of content and constant refreshing. With users contributing from all over the world on a wide variety of related topics, publishers will be able to have content which is accurate and up-to-date. With so much content generation turned over to users, overhead costs are kept low with staff kept at the barest minimum (admin and managers only). Also, since all production (apart from oversight) has been turned over to the users, you will find that you get information from locations you don't have the fiscal resources to cover.
Another advantage is that targeted traffic becomes a reality, as wiki pages will attract experts into that community. If as a publisher you cross your T's and dot your Ia's, don't expect great literary tools to be used on wiki sites. But you definitely will be more up to date than so-called "expert sites" in the same category. Note that sometimes a wiki site can take forever to complete its content, and also that ALL the content needs to be seriously edited for the readers (not every one that contributes will have good writing skills). In short, a wiki approach is well worth considering for building a new site or injecting life into an old one.
Website Promotion 
