Wiki
Originally Wiki Wiki, is a way to use the web to collaborate. A perfectly good sentence but explaining what it means is a little difficult. On the simplest level it’s simply a simple way for a group of people to create a web site; the Wikipedia is the best known example, but Wikis are being used to do all kind of things. If you have a group or a project that you’re trying to coordinate Wikis are definitely something that you should explore. Here’s another video from the folks at commoncraft to explain how it works:
Right at the moment we’re exploring two Wiki hosting services, both are free:
Wetpaint Wiki is perhaps easier for the novice user; you do have to read the screen and explore a bit. Wetpaint is Ad supported but if your wiki gets used the Ads will be relevant to your area and topic.
Wikidot is also free and this time no Ads. It assumes a bit more knowledge on the part of the user and is therefore perhaps a little more powerful.
If neither of these suit your taste here’s a list of Wiki Farms via Wikipedia.