[bitskits]

Within Google there are several tools, but the most common (and IMO best) is markdown. (Docs is a close second.)

Pros: Get's checked in like code, gets reviewed, and leaves a nice paper trial of edits.

Cons: Doesn't invite comments/discussions as well as Docs does.

[puzzle]

For many years there was also a wiki that just didn't refuse to die. I think that when I left there was yet another attempt going on to migrate the content away from it. Surprisingly, one of the main appeals was that its availability was independent of Google's production environment (Borg, GFS and co.). If Docs or Sites were down, which was slightly more likely inside Google because most employees were on dogfood builds, it was going to be a fun day...