Not surprisingly, there are already vultures looking to take advantage of the tragic earthquake in Haiti for their own financial gain. The Internet Storm Center (ISC) has posted this:
Domains being registered about the Haiti earthquakes already
At this point we don't know what are being registered for reasonable purposes and which ones will be used by scammers and con-artists. Inevitable some are registered for use by the latter group. Therefore, be careful when interacting with anything purporting to be related to the Haiti situation. In the past these types of people have used email, websites, Twitter, Facebook, MySpace, and whatever other vectors they could to fool people into opening up something or going somewhere where they shouldn't. Times like these are when people let their guard down for more news, for a chance to help, etc. And these folks look to take advantage of that.
The best bet is to stick to known legitimate sources for information and for providing aid. Some of these are taking new forms, such as SMS donations on Twitter, so it can be hard to determine who is legitimate and who isn't. If you aren't sure, stick to the ones you knew before the incident were such. Also, look for legitimate sources of information to indicate who is real and who isn't. For instance, another ISC post:
SMS Donations Advertised via Twitter
They've listed a couple that should be legitimate. But if you're in doubt, go to the old stand-bys.