Whilst the Red Cross is, of course, always a safe pair of hands for making sure that money reaches disaster areas quickly, safely, and effectively, I am aware that some people prefer to make use of a Catholic charity for this purpose; and there are those who, for all sorts of reasons, do not choose to use CAFOD.
US-based Catholic Relief Services has set up a special website to handle urgent donations for Haiti, and as they already have some 300 staff on the ground there you can be sure that the money will be making a difference quickly.
If you are considering a donation, and don't know how to deal with it, you may wish to have a look at the website and see if CRS meets your particular criteria : I understand from a US News site that Bill Gates (of Microsoft) has already sent them $1 million for starters !
Fr Tim has recently posted this, about the work of Missio in Haiti; and as you will see, it provides details for donating to them as well.
As they quite clearly say, this isn't 'disaster relief'; this is about long-term support for putting the country back together : but both are important, so do please think about supporting Missio.
Fr Tim has now posted further details which have become available of ways of supporting the immediate work of disaster relief through Catholic charities.