List of social media sites' "for good" programmes for charities/nonprofits

I've just searched to see if there is a single list of social media sites that offer "for good" programmes for charities or nonprofits. In other words, programmes that give them free accounts, access to enhanced services, additional training or resources, or some other benefit.

I can't find such a list. If you know of one do please share a link to it below.

Meanwhile, here are the services I'm aware of.

I'm focusing only on social media, not all online fundraising tools, or others that have social media application (so I don't plan to cover offerings such as Salesforce.com Foundation etc).

Facebook for Good
www.facebook.com/facebookforgood

Flickr for Good
www.flickr.com/good

Google for Nonprofits (covering Google Grants, Checkout, Google Earth, Google Apps etc)
http://google.com/nonprofits

Google Earth Outreach
http://earth.google.com/outreach/index.html

MySpace IMPACT
www.myspace.com/aplaceforimpact

YouTube Non-profit programme
www.youtube.com/nonprofits

What else is out there? Some of the above are only available to organisations in particular countries, so if you do suggest another one, please indicate if there are any geographical restrictions.