I found the entry for 'Applied Linguistics' by James Lantolf, in Malmkjaer's
The Linguistics Encyclopedia, Second Edition (Routledge 2004), to be a good "starting" point.
Main Points: Applied Linguistics -
1) relates primarily to the teaching and learning of specific languages (initially the focus of the discipline was on English)
2) However, it has expanded to include more than language teaching and learning e.g. language policy and planning, lexicography and lexicology, speech therapy, multilingual and contact language studies, assessment, SLA, literacy, forensic linguistics (some would even include stylistics, genre studies, discourse analysis, sociolinguistics, translation and interpreting etc). Generally, there has been a gradual shift towards more of an interest in social phenomena.
3) 'Despite its prosperity, the field continues to be nagged by a lack of agreement on the precise nature of AL...What precisely is applied in AL? Is there a theoretical component...or is it only a practical discipline? The early Edinburgh School considered applied linguists to be consumers rather than producers of linguistic theory. The task of AL...was to interpret the findings of linguistic research...in order to inform language teaching. ... (Widdowson rejects this) understanding of AL as "linguistics applied", since most language-based problems cannot reasonably be solved through the application of linguistic principles alone. ... Widdowson recognizes the necessity for AL to draw on disciplines outside of linguistics in order to develop its insights and recommendations.
One reason for drawing a distinction between AL and linguistics applied is the worry that, as linguistics itself expands the domain of its own research beyong theorizing about autonomous and abstract grammatical systems to recognition of the relevance of context for language use and language learning, the narrow interpretation of AL as linguistics applied could well make redundant the work of applied linguists.
Another matter of controversy concerns the brand of linguistics that should inform the activities of applied linguists (there follows a short discussion of "creativity" a la Chomsky, versus processes of e.g. the ability to create new meanings through metaphorical use of form).'
4) Grabe propses that in addition to TG, AL draw upon i) functional and typological frameworks e.g. the work of Halliday, Comrie and Greenberg ii) anthropological linguistics and sociolinguistics, and iii) research which results in descriptive grammars based on corpus linguistic analyses.
5) Is SLA (especially that within a UG framework) really about solving real-world language-based problems?
6) AL ' seeks to uncover and understand the sources and consequences of problems that arise when people experience difficulties fully participating in (old and new) communities of practice and attempts to (develop appropriate means to) help people (overcome) such difficulties. ... All of this clearly distinguishes AL from linguistics proper, which has as its object of study language, not people.'
If I was going to do a course, I would want it to concentrate on how people mean this and not that (using e.g. English as an L1 vs L2), in natural vs. classroom contexts, not on how they mean anything at all in any language. I believe that a theory of ("language" in) mind and society/social-developmental processes - as supplied by "Cognitive" Linguistics - is an interesting corollary to, but no replacement for an empirical understanding of the (English) language as (attested) fact: the forms themselves are more or less arbitrary, but there is a systematicity in their use. This is where e.g. Systemic-Functional Grammar would come in handy, in classifying the mass of detail and allowing generalizations to be made beyond whatever limited predagogical grammar. SLA, especially the socio-cultural models, would be an interesting sideline too, and valuable in suggesting an appropriate methodology, but there are no firm conclusions just yet, so the priority would remain, for me, or the language and trying to discern a "natural methodology" within it. I'd also appreciate it if a course could briefly cover or allude to "linguistics proper" at the start or from time to time, just to confirm that the (alternative) line being taken by the course was "justified"/semi-principled, even if not entirely original/non-reactionary.
These general books are all well worth a look:
The Handbook of Linguistics (Blackwell)
The Linguistics Encyclopedia, Second Edition (Routledge)
Trask, R.L. Key Concepts in Language and Linguistics (Routledge)
Crystal, D. The Cambridge Encyclopedia of Language
Crystal, D. The Cambridge Encyclopedia of the English Language
Carter, R & Nunan, D (eds). The Cambridge Guide to TESOL
http://www-writing.berkeley.edu/TESL-EJ/ej29/r9.html
http://www.eltnews.com/features/eltbooks/009.shtml