I used to keep a huge Notepad .txt file of a ton of company knowledge, gotchas, offhand documentation, and any kind of tidbit that I might need later. A few years ago, I migrated all of this to OneNote with detailed, formatted notebooks for every broad subject I could categorize. I recently shared my OneNote notebook with guys relatively new to my team, and I found them using it all_the_time. So not only is the "Knowledge Log" good for you, it can also be a useful tool to help others on your team.
At my old company, whenever anyone had a question about the system, we'd reply back with a link to a wiki page with the answer. It worked pretty well. We could either create the wiki page, update it, or refer to an existing one.
This is a good solution. That way, knowledge hoarding is often averted if the creator is willing to add info when it's fresh or lacking a procedure, and finder searches the docs before asking.
I really hate the antique-mindset, amateurish shops where they don't use DVCS, wikis, or configuration management. "Oh yea, only Jim knows how that works" is one signal of intense knowledge hoarding.
