Online Dictionaries

ENGLISH-ENGLISH DICTIONARIES

www.collinsdictionary.com Very good sample sentences
www.merriam-webster.com Most used American dictionary
www.macmillandictionary.com Very good for finding collocations and synonyms
www.oxfordadvancedlearnersdictionary.com Oxford Advanced Learners Dictionary
www.oxforddictionaries.com Oxford Dictionary Online
www.ldoceonline.com Longman Dictionary of Contemporary English
www.dictionary.cambridge.org Cambridge Online Dictionary
www.thefreedictionary.com The Free Dictionary
www.dictionary.reference.com Fun word games
www.yourdictionary.com Your Dictionary

ENGLISH-GERMAN DICTIONARIES

dict.leo.org Good translations, excellent collocations
www.dict.cc Good translations, good collocations
www.linguee.de Sometimes, but not always useful

FUN FLASHCARDS

quizlet.com Simple, FUN, way to learn vocabulary