Good ole' cheap as hell U.S. Army issued blanket. Either it's sitting in your garage already, your attic, up in the closet, or waiting for you at an Army Surplus store. This is oddly is one of the best accessories in anyone's shop.

It has a lot of uses and properties:

1. Mark one side so you know what's the dirty side, lay it down on the ground so you don't get dirty kneeling and laying on it.
2. US Army blankets are 100% wool, wool isn't really fireproof. But firefighters all know that wool doesn't sustain a flame, so it can be a house saver in case of a fire if you need something to smother a flame. No replacement for the right extinguisher, but if it's gonna be around anyways. Worth knowing!
3. When taking apart something that has more nuts, bolts and washers than you've had birthdays. It can help you keep track of the order of things. I put down a long strip of masking tape. As I remove those nuts, bolts and washers, I lay them down in a line along the tape in the order I removed them. When it's time to reassemble, just follow the line of parts in reverse. The masking tape also lets you write some notes down for how much torque each of those bolts will need.
4. Having your bike sit on top of the blanket can lessen the chance of losing those tiny nuts, bolts and screws. The dark green makes for better contrast for spotting the grey metal components that drop, that otherwise get camouflaged with the rest of your grey concrete garage floor. Also, since the blanket is soft and textured, when those tiny parts drop on it. They don't bounce and roll away as easily.
5. Works as a makeshift arm shield when working near your exhaust when it's still 700ºF+, wrap it around your forearm so you don't burn yourself as you make a quick reach in. Since it's 100% wool, it doesn't melt to you or your pipes.
6. Rolls up to make knee pad for all that getting down low work that makes you feel old.
7. Really absorbent in case of an "Oh shit!" moment.

Countless possibilities and cheap too. Even get one for free if you enlist and put in a few years!

The oil drain plug on my Honda is a pain in the ass. It's in a spot you can't get a socket on, it's wedged in tight between the motor and the frame, hose in the way. Even worse is there is a molded obelisk of metal extending from the case, which prevents getting any travel with a wrench. Gives me about 20º at best! Can barely get your hand in there to twist the bolt once it's free, and of course, the bolt has a mile of fine threads to go thru before it can be extracted.

As I said, real pain in the ass.

Tip: If you even encounter one of these engineering masterpieces, a solution is to use a shoestring. I use a long leather boot lace as it seems to grip better. Break the bolt loose with a wrench, loop the string around the head of the bolt, grasp the lace and give it a long smooth yank.

More ergonomic and less swearing, until the bolt falls in your oil pan.