I feel heartsick for the people of Haiti, who have already suffered so much from devastating poverty, political turmoil, and the dual epidemics of HIV and tuberculosis. Port-Au-Prince has been catastrophically damaged by the recent earthquake and the nation is being battered with aftershocks. If you'd like to help, here are some reputable organizations that are mobilizing resources:
American Red Cross
AmeriCares Help For Haiti
HaitiArise
Haiti Emergency Relief Fund
Mercy Corps
Partners In Heath (I can personally vouch for this stellar organization, which is already doing important work in Haiti)
Image from here with thanks.