Check out some packing lists, here or on
Crazyguyonabike and you'll get an idea of the range of stuff people bring along. But you essentially need camping supplies, food, water, and a change of clothing. Bike-specific tools and supplies (e.g., spare tubes, a pump and a multitool) are pretty much the only things you'll need to add. Heck, I've heard of people touring with a hiking backpack rig and a full-suspension mountain bike.