There is a terrific ESL specialty bookstore in Burlingame, CA, just south of San Francisco.
Alta Book Center- click here for their website
Alta Book Center - Materials for Teaching and Learning English.
They have a fantastic array of books, tapes, and other materials like games and flashcards.
If you live near San Francisco, it is worth a visit! They also offer free teachers' workshops. But even if you live far away, their website and catalog are very helpful and complete.
Martha