I'm not sure if this really qualifies as a kitchen "gadget" as it is super low-tech, but I am still bestowing it with the title 'My Current Favorite Kitchen Gadget'.
To the untrained eye this may look like an run-of-the-mill shot glass. In fact, I included one in Gretchen's recent birthday package and when she fished it out of the gift bag she questioned, "Ah, it looks like a shot glass."
"Ah... but it is so much cooler than that." I responded.
To be fair, we are getting a bit old to be giving each other souvenir shot glasses.
Anyway, if you cook even a little bit, you must be familiar with the standard set of dry measuring spoons. These little sets always cause a bit of kitchen havoc for me. The first problem is: if you only use one spoon, for say, a tablespoon of flour - do you wash to whole set? Another issue is that if you separate those little buggers - forget about ever finding the 1/8 teaspoon ever again! Finally, if you are baking, it is a pain in the butt to use the 1/4 teaspoon for salt after you just used it for vanilla.
That's why the mini-measuring cup is a genius invention. Labeled on various sides with different increments of measurements (tablespoons, teaspoons, and ounces) it is the perfect tool for all of your small liquid measuring. I love it for soy sauce, olive oil, water, and even honey.
They generally run under $5.00. Look for it where kitchen supplies and/or bar tending supplies are sold.