Additional Sources to Look At:
This Youtube video is from the Case Foundation, which is a foundation that focuses on using social media for good for nonprofit organizations.
The website for the Case Foundation, while focused on nonprofit organizations, has information about how to effectively use Facebook and Twitter, as well as blogging, to make a positive impact.
Examples of how social media has been used for good in the past
Using a hashtag to raise awareness
Using social media to raise money for charityhttp://mashable.com/2009/04/02/social-media-charity-events/
Negative impacts of social media:
One high school student thinks social media has negative impact, makes a tumblr blog to help
Examples of negative impact of social media on society and individuals