Here is some stuff that I talk about enough that I figured I should have them listed somewhere for you. (There should be an Amazon widget above this; if there is not, please reload.)
Humidifier: (in the winter, at least) Congested? Face hurt? Sinuses killing you? Nasal passages feeling cracked? Get one of these and point it at your face when you sleep. As a bonus, it’s great for your complexion. Do empty it out and let it dry in the mornings. If it’s gotten scaly, scrub it down with a vinegar solution. If it’s gotten slimy, rinse the heck out of it and soak it in a bleach solution (about 1 tsp to a gallon of water). You’re going to want to give it a good cleaning probably once a week.
Biteguard: Do you grind your teeth? Do you balk at spending $500 at the dentist? (Do that, at least the first time, though, really.) I have been wearing biteguards for as long as I can remember. I have been professionally fitted enough times that I know how my jaw should set. The SISU is by far the best OTC biteguard I have encountered. Custom and very durable. Just check the hot water with a thermometer so it doesn’t stretch too much when you are fitting yourself.
Water filter: I am just more comfortable if I drink a lot of water. body weight in pounds/2 = target daily water intake in oz. Bottled water is an ecological nightmare and just doesn’t make economic sense.
Arched footbed: I have 2 pairs of these and swap them around all my shoes. If you’re on your feet a lot, invest in comfort!
Neti/bottle: Allergies? Sinus issues? This feels so good. Really. Breathe through your mouth while you’re rinsing, and make sure the water is at a comfortable temperature. Do drain them every day and toss in the dishwasher every week or so. If you are unsure of your water quality, use distilled. And after you run out of the packets, you can use a quarter tsp of salt with a pinch of baking soda.