In your opinion what is the most successful Non Profit Organization utilizing social media to encourage change?

[LosPumas]

In your opinion what organization has used social media, twitter, Facebook, the internet, the best to get their message out there? For example, Peta, Amnesty, etc.

Please give the name of the Organization and an example.

[Has Compassion]

I would say ASPCA.ORG because many people are sympathic towards dogs & cats and are offended by how other people can abuse them... several celeberties donate their time to make ads for them, so people are more willing to donate to an org who is trying to ease that abuse.