Darius Goes West is a great example of social media being used for social change. The social media aspect is well integrated (and quite prominent) into the whole movement for a cure/awareness of Duchenne Muscular Dystrophy (DMD). Darius Goes West started as a documentary of Darius Weems going to California with his friends (and leaving home for the first time) to get Darius on MTV's Pimp My Ride and have his wheelchair customized. The film ended up creating - and still is - a lot of money and awareness for this disease.
To talk specifically about the social media aspect of this film-turned-foundation, on the website there is a blog with updates on Darius' health, upcoming events to raise more awareness/money (for example, his 21st birthday is coming up and there is a charity poker event to celebrate), and various deals (for example, educators can receive a free DVD). DGW also has a Facebook page and a Twitter account. On the Facebook page, there are songs (Darius is an aspiring rapper), photos, and articles. Also while not created by or specifically for Darius Goes West, this foundation is participating as one of the "hidden treasures" in Geocaching, where people from all over the world use GPS to find "treasures" in the real world and then share them in an online community. The DGW DVD was made a "geocache" by a Georgia teacher who wants the DVD to eventually travel to the West Coast and back, like Darius did himself. All of this, of course, was posted on the DGW's blog.
All in all, this organization really knows how to use social media for social change to help appeal to a younger audience. As an organization who chooses to produce the film independently despite offers from production companies) in order to continue to give the majority of the profits to DMD research, it has really gotten creative on how to get the word out and keep the excitement up about the organization. Social media are perfect for this type of organization that is small and therefore cannot spend a lot of money to do marketing.