I ride with panniers most of the time, so I carry a fair bit!
Three tyre levers, chain break tool, adjustable spanner, three normal spanners, multitool (Leatherman imitation, which has pliers), ratchet screwdriver with multiple heads & small sockets, mini foot pump, 2 x spare tubes, bicycle multi-tool, spoke tool, patch kit, self adhesive patches, sticky plasters, paracetamol. In addition, I sometimes (though not always) carry a small gas stove & a small kettle, a water bottle (for coffee, not my normal bottles), a cup or two, some milk, sugar (well, actually Splenda) and some instant decaf coffee.