I've only been on a couple of short tours since re-taking up the touring game after a couple of decades out of the saddle, so I'm still learning my way around the packing process. But, seeing as you ask...
On rear rack - tent, sleeping bag (in compression sack), sleeping pad. Held in place by a combination of bungee cords and luggage net.
In bar bag - iPod, Camera, book, map, snacks, lunch, multi-tool, notepad and pencil.
In front panniers - spare clothes, food, cooking gear, plate etc. Split reasonably evenly.
In front pannier pockets - tool kit, pump, puncture repair stuff, spare tubes etc. Split reasonably evenly.
Water in 3 bottles on frame, and as necessary, strapped to back rack.