If you like Wikipedia, then you'll love Microsoft SharePoint.  Not only can you create wikis, but you can create document libraries that allow for check-out/check-in capabilities, meeting workspaces to hold all of your meeting-related information, picture libraries to hold your images, tasks (think lite version of Microsoft Project), web logs (blogs), discussion boards, forms, surveys and much, much more.  Click here to see the presentation: Introduction to SharePoint.