I propose a new toggleable mode for the Magic Wand tool that would add some of the functionalities of the brush tool:
-Pixels will only be affected within the circle of the brush (in other words, the magic wand will have an adjustable range/size it affects).
-This functionality could further be expanded by allowing the brush to be softened, or even have custom brush shapes, pressure sensitivity, opacity, flow, etc. This would result in something similar to painting with such a brush in quick mask mode, while still having the Magic Wand's tolerance setting in effect.
-In this mode the magic wand will be draggable (the same way you would draw with a brush) and the brush's "spacing" setting will determine how often a new selection is made with the magic wand and added/subtracted (depending on current setting or key modifiers) to the existing selection. A low setting will make selections more often, but could be laggier.
How this can be useful:
If you have a bright and a dark object on the same white background, you can use this mode to refine the selection around the dark object with the magic wand without affecting the selection near the bright object. This situation is more common than it sounds - for example a white shirt and dark jeans on a white background. With the current magic wand, I can't use it to select the jeans without deselecting parts of the shirt as well. Also the "dragging" functionality would be hugely helpful when you have your tolerance set to a small value and have to click repeatedly to get all the nuances of the background - now you would just drag it around a bit and have a good selection, without worrying about affecting other parts of the image.