All As One -West Africa
http://www.all-as-one.org/ - Volunteers are needed in a number of areas - some that require specific skills and others that simply require a passion for the orphaned and destitute children of Sierra Leone.
Global Rescue Mission Sierra Leone
http://www.grm-sl.org/ - Their mission is to serve the most vulnerable in society - youth, women and children.
Campaign for Good Governance
http://www.slcgg.org/ - Increases citizen participation in governance through advocacy, capacity building and civic education.