Language acquisition made practical
Still probably the best field guide to language and culture acquisition in a self-directed and non-academic context. The technology is dated, it still suggests that learners use hand-held tape recorders rather than a digital MP3 recorder or one of the many other high-tech developments available to learners today. But the principles behind the method are the most solid and best explained I've ever seen. I used this method to learn Japanese for 2 years and then facilitated many others' use of it as well. Language learning isn't an academic subject, it's a social enterprise.