I've recently used Trac to create a little personal Knowledge Base.
The only aim of this Knowledge Base is to centralize access to various quick information corresponding to specific computer science issues/situations.
Initially, I've set up this system for personal purposes.
Nevertheless, if you find current tickets (Knowledge Base elements) interesting and you wish to add some yourself, send me an email to admin[dot] knowledgeBase[at]bsquare[dot]no-ip[dot]org.
There is currently very few tickets (lack of time), but as soon as possible, I'll add more.