Tart warmers are sold in many stores, especially Yankee Candle. Basically, instead of using a candle, you melt a small, wax object called a tart. Tarts are scented just like many candles.
You can choose from a wide variety of electric tart warmers or standard tart warmers that are heated by a candle. I personally recommend using the electric tart warmer. They are fun and inexpensive. Electric tart warmers also make great gifts!