Willy St. Coop is taking gift card orders over the phone. They collect the cards, and the next morning call the protesters, and send them what's needed. I've called them and sent some money, and it felt legit to me. (608) 251-6776.
Ian's Pizza (click on the Madison location after the page loads) is also taking money and using it to buy pizza for the protesters. I haven't called them myself, but saw this reported from several different people, and their blog mentions it. 608.257.9248.
ETA: Just after posting saw this other way -- Straight To Your Door, a multi-restaurant delivery service. This link is posted by one of the people who's been active in the Capitol all week, so you can rely on it: