American Airlines

United Airlines: This airline has service into San Jose from the following US-cities.

Delta Airlines: This airline has non-stop service into San José, Costa Rica from Atlanta, Georgia.

Continental Airlines: This airline has one flight each day through the Houston airport with connecting services from Vancouver and Toronto, Canada via Air Canada.

US Airway: This airline has flights into San Jose and Liberia from most of the US-cities.

Taca Airlines & LACSA Airlines: This airline has non-stop service into San José, Costa Rica from Chicago, Dallas, Houston, Los Angeles, Miami, New York, San Francisco, Oakland, Toronto, Washington

Spirit Airline:  A low cost airline with service to San Jose from Atlantic City, Boston, Chicago, Detroit, Fort Lauderdale, Fort Myers, Las Vegas, Long Island MacArthur, Los Angeles, Myrtle Beach, New York, Orlando,  Tampa, Washington,  West Palm Beach.

British Airways

Iberia

Virgin Atlantic

Mexicana

LTU

Jetblue a low cost airline out of Orlando

There are other airlines which have minor service out of Canada and the U.S.

Wiki article with list of Airlines serving  Juan Santa Maria

There are two international airports in Costa Rica.

One is located at Liberia which services most of the charter flights to the Pacific beach resorts. Continental Airlines and LACSA both have scheduled international services from the United States here.

The other airport is Juan Santamaria, 15 minutes drive to the capital city of San José.