ThoughtFarmer is an excellent "intranet in a box" product. They have just announced the release of their new version 3.6 - you can go to this page to read about the new features:
ThoughtFarmer 3.6: Relevant Home Pages, Easier Searching and Customizable Groups
However, even better than this, they now offer an 'instant demo' account, all you had to do is provide an email address, and they you can get access to a live server and play to your hearts content. I have sent off for mine, and will report back when I have had the chance to play with it a bit.
ThoughtFarmer instand demo sign up page