LAN
LAN offers service to most regional airports in Chile. They have a good multi-lingual website where you can make reservations.

Sample Prices (Jan. 2008, economy)
Santiago - Temuco - Round Trip starts at about $100US.
Santiago - Puerto Montt - Round Trip starts at about $110US.
Santiago - Punta Arenas - Round Trip starts at about $150US.

Website: www.lan.cl

Sky Airline
Sky Airline is a Chilean carrier with service to most Chilean airports, including Pucón, Temuco, Concepción, Osorno, Puerto Montt, Puerto Natales and more.

Website: www.skyairline.cl

AirComet Chile
AirComet Chile is also known as Aerolineas Del Sur, has service into Temuco, Concepción, Puerto Montt and other cities.

Website: www.aircomet.cl