USB Portable Humidifier
Turns a regular water bottle into a humidifier, powered by USB. You could add some liquid fragrances or essential oils to make the room smell nice. Great for the problem of dry hotel rooms and it's small enough to travel easily.
It has a wick that transports the water and dissipates it. Has a very cool blue glow that cna also serve as a nightlight, which is also very useful in a dark hotel room that you're unfamiliar with.
This USB humidifier automatically shuts off after 8 hours and comes with a couple of filters. The filters last a few months and are available for about $2 bucks each.
If dry air is a problem for you or your eyes get dry really easily, this is a nice little gadget to pick up!