Sumajin Smartwraps work with anything that resembles a headphone, and they cost $12.95 for a pack of three (black, white, and clear). That is somewhat pricey for three small pieces of rubber, but they have lasted me for at least four years and running, and they do one thing, well, that will save you time over the long run.
Gloves so you don't miss smartphone calls when you're outside
Living in Buffalo, NY, I can lay claim to having some expert opinions on at least one niche of the smartphone industry: gloves that claim they work with touchscreen devices. AGloves? Stylish, and conductive, but far too light for any winters except those presumably experienced in North Carolina (although I have not tried the "Heavy Duty" variety). Boiled wool Echo Touch gloves? I like mine well enough, but they're not especially attractive, and apparently now close to $40 each, if you can even find them in stock, which is nuts.
I tried on MUJI's unisex touchscreen gloves, along with the slightly heavier-duty neoprene touchscreen gloves at the MUJI airport store in JFK, and they're a nice mid-point. No matter what, you're giving up a small area of warmth around the index finger and thumb, because the physics of electrical conduct cannot be cheated. But the gloves are warm enough for most winters, and the conductivity is there to slide to answer a call, tap out a short message, or open your email.
There you have it: five boring but mildly life-improving gifts that you'll probably end up buying for yourself, because somebody else will buy an incorrect variant. What are the hopelessly nerdy and mobile-minded gifts on your own holiday gift list?