Another idea: if a tool like Captivate, or one of its cheaper relatives is made widely available, users might be encouraged to upload workarounds that they have created/discovered to a wiki or some other shared space.

I have often used a champions network in rolling out solutions to an organisation. If you get these people to post a tip of the week in a shared space, or even as a group email, it isn't a huge step from there to blogging. Another possible approach is discussion forums and FAQs, administered by the champions network.