Project Linus is a very cool sight from Gary's blog. "Linus" as in security blanket - they give security blankets "to children who are seriously ill, traumatized, or otherwise in need...[and]. . . to provide a rewarding and fun service opportunity for interested individuals and groups in local communities, for the benefit of children."
Another is Hugs Across America. This grass roots group started in a school in NYC in the aftermath of 911. They give teddy bears to children in disastor situations.