My scoops, my rasp, my fresh nutmeg mill and my insta-read thermometer.
I would have thought that every large grocery store would carry scoops...not so. I can't remember where I purchased mine, perhaps Sur la Table or Williams-Sonoma. But for consistency, accuracy and a prettier cookie, you can't go wrong. And, depending how many I'm feeding, I can choose either one...larger cookies, or smaller to go further.
My rasp. Back in the day, our sole means by which to grate things was the box grater. I still have mine, and use it for bigger grating. But, oh, the grated skin off the fingers was simply not part of the recipe. The rasp does the trick, and is long enough so that you don't keep hitting your hand on the cutting board while you're going in a downward motion. It has saved my skin...literally!
I think the least utilized, but something that makes a big difference, is my fresh nutmeg mill. You can buy whole nutmeg in the bulk section of pretty much any grocery store. And what I do is usually buy only 3-4 whole nutmeg and put them in the little storage unit in the mill. You just plop one in the middle of the mill and there are little teeth to grab hold. The smell of freshly grated nutmeg matches no other...just like grinding fresh coffee...it just puts you somewhere else. A few places this little tool comes in handy is on top of homemade eggnog, in pumpkin pie, in the gravy of true Swedish meatballs and my recipe of Potatoes with Leeks and Gruyere. And it's not a big expenditure.
There are two things when my insta-read is a must...gauging the temperature of a small rib roast and making sure water is the right temperature when adding dry yeast so it will proof properly. I've had it many, many years, and even though they make some real nifty ones these days, as the old saying goes, "if it ain't broke, don't fix it.