Language immersion camps have been around for a long time. Middlebury in Vermont is an example with a long history: http://www.middlebury.edu/ls/approach/pledge Like study "abroad" at home, the programs offer students an academic environment for learning the language through immersion without leaving the country. In the Midwest, there are the Concordia Language Villages: http://www.concordialanguagevillages.org/newsite/Languages/spanish1.php Some campuses have language houses:
Where I teach here at Valparaiso University, we have a World Language Village in one of the nicest dorms on campus. The deadline for the Spanish House is coming up in January. Check it out: http://www.valpo.edu/foreignlanguages/spanish/spanishhouse.php
Does making a promise to speak only the target language really work? Middlebury has the trademark on the term "Language Pledge". Asking a group to abide by a single language during an immersion experience has mixed results, according to students I know who have done these programs. A key, I believe, is having particpants on board with the idea of signing a promise. Also, there must be reasonable consequences for speaking, reading or writing anything but the target language.
Being aware of the positive outcomes of such an immersion experience is key...especially when suffering through the headaches and frustrations of trying to spit out what you're trying to say in another language. In essence, to learn a language through immersion, a person has to WANT to. When I spent a year in Barcelona as an undergraduate with students from universities in California and Illinois, there were students who were already fluent in Spanish in our group. There were others whose Spanish sounded just like the textbook, with an American accent (I was one of those!) I pledged with myself early on to be wary of befriending Americans, and to speak as much Spanish as possible. I chose a home stay option with a Señora who spoke no English. I spent weekends meeting people who spoke Spanish and Catalán exclusively. I particpated in a few "intercambios" (language exchanges) but found that I was giving English lessons during the precious time that I could be speaking Spanish with people who didn't want to use me for my English-teaching abilities. I felt very selfish--but my theory worked, and I learned a ton of Spanish in my year in Spain.
What about studying local culture right here among the Latino community in Chicago? This week I am learning more about a program organized by the Mexico Solidarity Network on immigration and community organizing. http://mexicosolidarity.org/ausm/alternativebreaks.
We have great local resources for learning language through immersion. Potential new friends live all around us! Having the motivation and the "I want to and I can do this" attitude helps a lot, too.