Portable Humidifier - USB powered / attaches to any bottled water. As long as you re-used the bottle and didn't add to the landfill collection of plastic, I think this'd be a great idea for travellers.
URBANO ECO TRASH CAN. Store and use grocery bags for your bathroom trashcan. Good way to recycle all those grocery bags instead of throwing them away or letting them sit somewhere! Plus you don't have to buy garbage bags for your bathroom!
Natural Herbicide Weed Killer: vinegar, 1 T liquid soap, 1 T salt, Dog cone Mix first three ingredients in spray bottle. Will kill anything it touches. Place dog cone over weeds. Spray, don& pour or nothing will grow there for a while.