Diccionario monolingüe
bilingual dictionary
PICTURE DICTIONARY.

A program to record audio files: audacity
Flash cards maker:http://www.kitzkikz.com/flashcards/
Plataforma segura de contacto con centros de otros países del mundo: www.epals.com
Interesting tool to create vocabulary cards: www.wordle.net
Crossword puzzle and word search creator: http://www.puzzle-maker.com/

Helpful guide to English pronunciation:

Some differences between British and American English, according to Cambridge: