Central America
Mesoamerican Ecotourism Alliance - http://www.travelwithmea.org/
Offers unique ecotours to Mexico and Central America with a variety of activities including white water rafting, trekking, snorkeling, birding and archeology sites including Tikal and Copan.
Swiss Travel Costa Rica - http://www.swisstravelcr.com/
Costa Rica travel agency, offering one day tours, groups, cruises, fits, and incentives.
Costa Rica Tours - http://www.costaricatour.com/
Offers general information about Costa Rica, and sample travel itineraries.
Nature Tours - http://www.naturetoursinc.com/
A wholesale tour operator specializing in travel to Belize, Costa Rica, Guatemala, Mexico and Panama.