Costa Rican Green Building Council:  Recently formed in 2008, The Green Building Council of Costa Rica (GBCCR) is a nonprofit organization that certifies sustainable businesses, homes, hospitals, schools, and neighborhoods. GBCCR is dedicated to expanding green building practices and education. This is a good place to start additional research.

U.S. Green Building Guide: Not a Costa Rican organization, but the U.S. body from which the GBCCR will take LEED principals to be modified for tropical living

Green Architects 
Bruno Stagno Arquitecto – Costa Rica's leading green architect.

Instituto de Arquitectura TropicalSan Jose - Bruno Stagno's Architectural Institute for Tropical/Green Building.

EcoArc - Local to Tres Rios area with a sustainable design philosophy

Luz de Piedra  - A San Jose architect with a sustainable design focus

Green Building Materials
Madera Plastica - Range of boards, panels, beams made from recycled plastic designed for use outdoors

Agua Solutions – Liberia – rain water harvesting and catchment systems.

Solatube – Costa Rica distribution of U.S. products to bring in natural light without the sun’s heat

Alternative Energy  
According to the IAEA 98% of Costa Rica’s electricity is produced from hydro, geothermal and other renewable sources so connecting to the grid is quite green already, but you can supplement it with other mechanisms.  In addition it's possible to install residential systems able to sell electricity back to ICE.

Solar Renewable Energy Solutions: San Jose - provider of solar, micro-hydro and wind solutions

Poderco – Puerto Jimenez, Osa - renewable energy systems, backup power systems, water supply and sustainable solutions

SourceGuides for Renewable Energy – online – additional list of Costa Rica suppliers

Other resources
Rancho Mastatal - Central Pacific - environmental learning and sustainable living center, retreat and lodge located in the last virgin rainforest of Costa Rica’s beautiful Puriscal County.

Jungle Chocolate - Puerto Jimenez, Osa – Fine organic chocolate from Samaritan Xocolata using organically grown chocolate, vanilla, and chili by Kimberley Blackwell