Activated display phones in AT&T stores are fun. You can send dirty text messages to strangers or make long-long-long distance calls. What this individual did is far better than any prank though: He donated money to Haiti on AT&T's behalf.
I'm assuming that this person donated $10 at a time by texting HAITI to 90999. Whether AT&T will actually release the funds is uncertain, but kudos on the effort. Now, if you'll excuse me, I'm gonna take after a few Redditors and visit my local cellphone stores to send a few text messages.
In the meantime, please keep in mind that there are many ways to donate to Haiti aid and that Lifehacker has a great guide on avoiding scams along with plenty of links to help you make sure that your money goes to someone in need. [Reddit—Thanks, Marc!]