My colleagues at Ushahidi have already swung into action and are mapping crisis information from Haiti. (Disclaimer: I'm on the board). For those you who arenot familiar with Ushahidi, they have a platform that allows anyone to gather distributed data via SMS, email or web and visualize it on a map or timeline. Their goal is to create the simplest way of aggregating information from the public for use in crisis response.
They also have a list of charitable organizations/ngos doing work in Haiti that need donations - like Partners in Health. If you want donate, make sure you keep your scam filter active ... You can also text to give to the American Red Cross: Text HAITI to 90999 donate $10 to the Red Cross for Haiti efforts. You can donate $10 up to three times, and 100% of the donations will reach the Red Cross Foundation. This effort is run by Mobile Accord. $3 million has already been donated.
MobileActive has an aggregated list of places to donate or find additional information.