Pretty much everyone enjoys a nice soak in a hot-tub. It's much fun to either soak away the day's sore muscles by yourself, or enjoy some wine and companionship in a relaxing setting.
The problem that many people who are the owners, not the users of hot-tubs are the cost of running them. The cost of the chemicals, and more importantly, the cost of heating them. Not to mention that if you want to take it to your cabin in the mountains, you're relegated to the soft-sided propane-fired versions.
Not so anymore.
The Dutchtub is a molded-plastic tub that uses a firebox and the thermal difference to pull colder water from the bottom, and flow it back into the top. Making it light, portable, and cheap to operate. It heats up quickly, and even comes with a wine-chiller and optional grill, so you can make yourself a steak while waiting for your tub to heat up.
Now, you've got to make your own bubbles, but it's still a great idea..