Grammar:
http://www.dartmouth.edu/~german/Grammatik/Grammatik.html
http://www.german-grammar.de/grammar/content/english_german_table_of_content.htm
German beginners (interactive powerpoints):
http://webgerman.com/Animated/
Flashcards:
http://www.foreignlanguageflashcards.com/language/german
Vocabulary:
http://www.learnalanguage.com/learn-german/german-words/
http://www.digitaldialects.com/German.htm (all levels)