For riders:
1.) Earplugs.
2.) GPS that has self-correcting ability, easy to use (Garmin 660 is quite good).
3.) Rider-to-passenger communication system that works well (read: must have squelch mic sensitivity that is adjustable while riding).
4.) A Camelbak that works well.
5.) Thermal / Insulating underwear top and bottom.
6.) Modular helmet (reduces a bit of fatuigue at each stop (fuel, bathroom, eating, speaking to others for directions, campground attendants, etc.).
7.) Fuel gauge on my bike.
8.) Accessible camera.
9.) Boots you can walk in.
10.) LED headlamp that can be worn on your helmet (for on-the-go map reading at night, don't ask...).
11.) $2000 extra dollars above your budget...
The best tool in addition to your bike's toolkit:
Alien bicycle multi-tool LINK.