I've been playing with wikis for a while and think they are a fantastic tool for creating websites without having to know HTML. Add in their collaborative properties and you have a tool that is fantastic for knowledge sharing and peer produced content, all of which were topics covered at the recent Jimmy Wales seminar here in Adelaide. They can be usefully used on an IWB, and I've been using one for my class planning during this year in preference to embedding everything on a flipchart. I've been using PBwiki which I chose as they had recently changed their interface to a friendlier user interface, getting rid of the need to know wiki markup language. It has been very useful as I embed all of the URL's for online resources in one spot and it's easy to track everything down. I can share the content with anyone and I can see this growing as an organic digital record of 2007.
PBwiki are also offering a bonus for anyone blogging about their product so my post can be construed to be somewhat self motivated, but seriously, their wiki is attractive, easy to use and is ad-free for educators. What more could you want?