First Aid Kits

The F.A.K. is an essential item on the trail...

Often overlooked on a touring biker's pannier, is the First Aid Kit. 
This will save your butt when you fall and if you are proficient, you can pack enough medication and wound management kits on the go.
Highly recommended are the pre-packed kits from Adventure Medical Kits.
These are sold in the US for as low as USD$7 for a personal kit and as high as USD$700 for expedition kits.
If you plan to haul, its wise to pack a simple first aid kit.
Stuff like wound closure adhesives, gauze pads, irrigation fluids and personal medication can be carried.