As I’ve mentioned a few other times here, I established a wiki for my organization’s intranet. It’s really taken off as a way for users to quickly and easily post and share documents. I mostly use it to post how to’s to nip in the bud the kind of support requests that eat away at my day. Very often I’ll get a ‘how do I’ question via email, spend 20 minutes posting a page on the intranet (complete with screenshots), and email the person back the link to the page I just made. That way I never have to answer that question again. In theory. Not all my people RTM if you know what I mean.
One thing that has helped as been creating flash based tutorials and posting them to the intranet. I use a product called Camtasia Studio by TechSmith. Essentially its just like doing a screenshot but using video and audio. I start it up, put on my headset, click record, and talk and click my way through the task. When I feel especially generous I add titles and callouts. Otherwise its a breeze to publish to flash and post on the site. I use an MediaWiki extension called Flashow to add Flash to the intranet pages.