If you like fireplaces but your home doesn't have one, a zero-clearance fireplace could be for you. It can be set on your subfloor and within an inch of other combustible surfaces. With glass doors, heat from inside the combustion chamber is circulated into the room through vents at the bottom and at the top, and room heat won't escape up the flue. They're lightweight, so you can place them anywhere, and you can install one within a day. Always check your local building code.
For more on fireplaces, consider:
Fireplace Maintenance Checklist
Pellet Stoves: An Eco-Friendly Heating Option
Gas Fireplaces: A Showcase of Design and Innovation