The Asociación Bio Itzá does great, inexpensive Spanish-language immersion programs for individuals or groups in Petén, Guatemala. It's a short trip from the Flores airport to their school and homestays in San José:
and it's also a short trip to Tikal:
They also have a school for teaching indigenous Mayan languages like Itzá, Quiché, and Kekchí.
There are some slightly cheaper language schools in Guatemala, but this one makes your money go a long way, since they use the income to preserve and protect one of the largest unbroken stretches of rainforest North of the Amazon, and to preserve indigenous culture, protect archaeological sites, and promote sustainable agriculture. In addition to learning Spanish, you can learn about medicinal plants; local cooking, music, and culture; rainforest ecology; Mayan archaeology (they have a licensed archaeologist on their staff); and a lot more. Students interested in rural medicine can ask about arranging to work in the local medical clinic. Worth every penny.
(Thanks to Luke Lynass and the other Augustana College students who worked to get this new website up and running.)
