Nothing says home more than a fire crackling in a hearth.Fireplaces have been a central feature in homes for centuries, but their design, technology and fuels have changed dramatically, especially in the past 10 years. Flames sprout out of torches or tureens; slip along a linear path through sand, stones or crystals; or blaze at temperatures hot enough to consume all the combustible material. A growing number of realistic electric fireplaces or new no-vent gas products can add a touch of warmth or just the mesmerizing flicker of flames to almost any space, even apartments and mobile homes. As higher fuel prices have consumers looking for ways to trim heating bills, many homeowners are looking at their existing fireplace as a more cost-effective source of extra heat. "While fireplaces of the past were widely used for ambiance, many of today's hearth products are very energy efficient and can help cut energy bills," observes Jack Goldman, president of the Hearth Patio and Barbecue Association (HPBA). Shipments of energy efficient fireplaces, stoves and inserts to retrofit existing fireplaces increased dramatically in the first six months of 2008 over the same period in 2007. Changed too are the number of options and anyone looking to upgrade an existing fireplace or add a new one is likely to be overwhelmed by the number of choices. "It's not simple like it was 20 years ago," when there were a couple of wood and gas burning fireplaces and wood stoves, says Bob Martin, owner of Monroe Fireplace & Stove in Monroe, Wash. Fuel sources, size of the firebox, heat or no heat, exterior finishes, classic, contemporary or country are only a few of the decisions consumers have to make. Gas is the most popular fuel today and 70 percent of hearth products burn gas. With glowing embers, coals, even crackling fire sounds many gas units replicate wood fires. In fact some designers specialize in this.