We used DocBook to write over 500 pages of process documentation for people to follow. After an initial learning curve with it, it was very easy to code up tagged text. Then it was convenient for it to translate into whatever format we needed, HTML, PDF, etc. That was the easy part. And I agree with other people here - keep it simple.

The hard part is getting anyone to actually read it and use it. Practically nobody did, and less so the further down the skill chain you went. What did work for us was holding regular in-service training sessions with everyone, covering one topic per week, and eventually getting everyone up to speed. We used the documentation as handouts, printing the relevant sections for them.

Popularity of a site and value of its content are not the same thing. While those sites may very well be popular, due to having plenty of mind-share, their content is by no means exclusive or essential. It's a rare day that I access any of the sites you mentioned, and yet I get the same or equivalent information eslewhere every day. If one of the sites I use becomes unavailable, for whatever reason, I'll simply find another, and that is why ESPN's strategy will fail them in the long run.

I've seen it called "Inrush Current"