This, and only this:
We Are The 99 Percent.
(If you, like me, were born between June 22 and July 21, and your first answer to "How can I help" is always "Feed them!", Liberatos Pizza (yes, by sheer coincidence, that's the place's real name, and the owner's name is really Telly Liberatos) has an online ordering system that you can use to order pizzas to donate to feed the protesters. Just tell them to deliver to anyone at Zucotti Park. They know what to do.)