I heard about this on the Slate Political Gabfest, and went and checked it out. Here it is from the Red Cross web site:

12:30am (1/13/2010) You can text “HAITI” to 90999 to donate $10 to American Red Cross relief for Haiti.

It’s a quick, easy way to kick in a little cash to help while you are thinking about it. It will be charged to your cell phone bill and can do it up to 3 times for a $30 limit. After sending the text, you will get a confirmation text to which you can reply “yes” and then two more that are just informational. Now you know.