Different ways you can help:
From Progressives for Haiti:
"Simply a cooperative effort among progressive citizens' groups to put provide immediate assistance to the people of Haiti, in response to the devastating earthquake there. Any group is welcome to participate by simply directing their members to this page, or else circulating this donation link: http://www.progressivesforhaiti.org/donate . No one involved is keeping any of the money raised, we're only passing you through to donate directly to organizations we've identified and vetted as doing real, immediate work on the ground in Haiti."
Progressives for Haiti has a 'DONATE NOW' button that links directly to Doctors Without Borders right on their homepage.
From mGive -
Early on the morning of January 13th a 7.0 magnitude earthquake hit Haiti and details are still coming in. mGive is working with the Red Cross and we ask you to help now with an immediate donation made from your mobile phone. Simply text the word HAITI to 90999 to give $10. When prompted, reply with YES to confirm your one-time gift. The $10 donation will appear on your next mobile bill and 100% of the donation will go to Red Cross to help those hit by this natural disaster. Receipts can be printed at mGive.org/receipt.
I recommend reading the comments attached to the link for this story. Some people with certain mobile providers had some difficulties. However, that shouldn't stop you from donating what you can to assist these people in need.