Chomsky is one of the theorists of language, but he himself has stated that his ideas have little application in the classroom. However, I feel that his ideas are worth reading.
For language teaching theory, there are many, but I'll give you a few:
Communicative teaching- Candlin and Widdowson
Lexical- Michael Lewis
Syllabuses (functional\notional) Wilkins
I recommend Whorf highly, though many find his ideas controversial
For usage, I like Michael Swan
For computer based views of language the Cobuild and Longman teams have a lot to offer.
