I usually take the following with me:
Cell phone (for safety);
GPS (or two) and spare batteries;
Compass (in case GPS units or batteries fail);
Digital camera;
Flashlight;
Heavy work gloves (for thorns, snakes and so on);
Small notebook and pen;
Swag items;
Custom (homemade) snakebite kit;
Pair of FRS radios (for talking with companions or other cachers);
Poncho;
Sun hat;
Wading boots (left in car if not needed but brought along if in heavy snake country);
Water and trail food in vehicle (in pack if long hike is anticipated)
