VoFair: Volunteer Fairly is a south american based organization bringing quality standards to volunteer projects using an individual designed certification system. The organization stands for values and quality standards within the voluntourism industry. They have a very informative website on which they educate about voluntourism.
VoFair also runs a Facebook page they use to inform about volunteering, voluntourism, general topics, development cooperation and their own organization. Visit their Facebook page for regular updates and contact them if you plan to volunteer in South America.