There is the openstreetmaps project, using xml .osm format:
"A new version of planet.osm is released weekly (currently
every Thursday morning). We have these, going back to the start of April
2006. The current size of a planet.osm file is over 171
Gigabytes.(reduced to 11GB with bzip2 compression) as of September 2010."
There is also WikiHow, http://en.wikipedia.org/wiki/WikiHow
They license their content with Creative Commons, yet they don't provide public dumps of the site. I have asked them to about this in the past on their forum with no luck so far.
----- Original Message -----
From: emijrp <email@example.com>
Date: Tuesday, October 12, 2010 6:47 am
Subject: [Xmldatadumps-l] Public dumps
> Do you know more projects which publish public dumps? I know
> Wikimedia,Wikia and Citizendium. Any more? I'm working in a tool
> for analysing dumps,
> and I want to add support to all of them.