I just made a donation for Haiti through Doctors without Borders. Not to say there aren't also plenty of other worthy charities, but it seems like Medicins Sans Fronteires has a long history of working with Haiti so they should know what they're doing.
I hear that the earthquake flattened the UN building in Port-au-Prince, killing everybody inside, so the people who could have been doing the coordination of the relief efforts all died. Plus the city's airport and main seaport were heavily damaged so it's harder than it should be to get people and supplies in or out. And the epicenter of the quake was almost right underneath the capital city and most densely populated area. In the poorest country in the western hemisphere. Long story short, they are in really really bad shape.
Couple of links:
This is a good article: How Not to Help in Haiti explains why you shouldn't try to help by sending stuff or by going to Haiti yourself, and why donations will still be needed long after the tragedy stops being on the news.
Ill Doctrine explains Haitian history: "We need to act not because Haiti is some nation of perennial victims that we need to have pity on. We need to act because Haiti is a nation of heroes and we have to repay them for what they've given us."
Ben Lehman is donating all proceeds from game sales this week to earthquake recovery organizations. Go Ben!