Some of mine were:
Pivot Pegz and adjustable gear shifter. A larger foot peg is great when standing off road, and since you shift thousands of times a day, depending on the terrain, having the gear lever hit your boot in the right spot is extremely important.
The infamous Tobinators, without which I would have a migraine headache after a few hours of wind buffeting my helmet around, and would have made the whole trip a disaster!! They allowed me to find a setting that put the windshield in a position to ride in quiet, and calm, comfort.
Easily the two most inexpensive and worthwhile farkles, a crampbuster and a cruise control. The crampbuster uses the heel of your palm to control your throttle, since gripping the hand grips for hours on end causes huge muscle pain. The cruise control you rotate round onto your brake lever and the friction keeps your throttle in one spot. Very helpful for huge highway miles. Each cost less than $20!!!!!
Jesse aluminium panniers. Extremely strong, and hold a HUGE amount of gear.
TomTom GPS and crossbar pad. I don't know how you can ride, or drive, long distances these days without a GPS! The motorcycle version is more expensive than the car version, mostly due to it having to be waterproof, and be able to accept commands while wearing gloves. Connects via bluetooth to your cell phone, for those all important phone calls while riding off road, and to the bluetooth speakers mounted in your helmet. The crash bar pad is just a safety item in case of hurtling forward....
BMW stock 1150GSA top box, worked really well.
Footpad enlarger for the side stand, so the bike doesn't fall over when you park in soft sand.
Handguard spoilers, add a bit more wind and rain protection.
Bottle holders, The left one held a one and a half litre fuel bottle formy camp stove. I bought a multifuel stove, so it used gasoline, so I it meant I always had a bit more in reserve if I ever needed it. The right one held a large aluminium water bottle, that plus the 2 litre Camelback meant I could make dinner even if there was no water around.
Finally the Barcalounger, or as it is really called a Russell Day Long seat:
The stock seat for the 1150GSA is a single motocross style seat, that while it works really well as an offroad seat, isn't really conducive to long distance comfort. The Russell is what all the long distance riders swear by, and I would have to agree. I bought mine used for half the price, and it was definitely worth the money!!! Even after a nearly 1000km day I never once had pain in my posterior!!
And finally a waterproof cover for the leather seat, by King of Fleece. Absolutely mandatory to protect your investment, and absolutely waterproof. It is stretchy, so is a perfect fit.
Not an inexpensive set of equipment, but since I plan on keeping the bike for a long time,and most of them hold their value really well, they all were a really good investment in my future travel. I don't believe that there is a gold plated toilet seat in the bunch. They were all used, and all performed at least as well as the cost to acquire them.
So unless something else pops into mind that is the end of this journey. So until next time, so long and farewell.