Well, Slashgeo.org is not really a charity, but it is a registered non-profit organization. (and since we have no revenue at all, I feel it’s closer to charity than anything else However, our objectives are clearly not as broad as “spreading the word about Geography and spatial thinking” at the moment…

I’d add GISCorps (www.giscorps.org) and MapAction (www.mapaction.org) to the list. Both focus on providing mapping services for developing countries. MapAction is primarily focused on humanitarian and disaster relief. GIS Corps has done this work, but are primarily focused on short-term voluntary GIS services to underprivileged communities.