Patch kit
Tire levers x2
Spare tube
Allen keys to fit the fasteners on my bike
Teeny adjustable wrench for the few hex bolt heads on my bike (will replace those with Allen heads, and dump the wrench)
Chain tool with the handle cut short
Dinky little ratcheting screwdriver that has Phillips on one side, flathead on the other (will replace this with a smaller screwdriver, since all it will ever be used for is limit screws on derailleurs)
Spoke wrench

On a long ride, add

Shift and brake cables
Another tube
Extra clipless pedals (the kind I use are very small/light, and a clipless pedal goes wrong on a ride, you are comprehensively screwed: low odds of finding a replacement at some small town sporting goods store).
Allen key for the pedals

I like the duct tape idea for sidewalls.