The other day I mentioned the work of Missio in Haiti. Fr John Boyle has a good informative post in which he gives a number of links to various Church based charities doing good work in the area.
He particularly recommends Aid to the Church in Need which is another excellent choice. They have contact with the Nuncio in Haiti so that funds can be speedily routed through one of the few administrative buildings still standing.
Yet another is the Knights of Malta which has been working in Haiti for fifteen years in support of a hospital. They are preparing to send an international medical team to support their people who are already on the ground.