General grammar exercises

http://www.autoenglish.org/index.html

http://www.autoenglish.org/freeexercises.htm

http://www.agendaweb.org/ 

http://www.grammar-quizzes.com/prestensum.html 

http://www.ego4u.com/en/cram-up/grammar/relative-clauses

http://www.myenglishpages.com/site_php_files/grammar-exercise-too-enough.php 

http://englishteststore.net/index.php?option=com_content&view=article&id=11504&Itemid=323%3f

http://www.learn-english-today.com/lessons/exercise-list.html

http://www.englishrevealed.co.uk/fce_grammar.php

http://www.grammarbank.com/english-for-beginners.html       grammar to all levels

http://www.perfect-english-grammar.com/simple-present-exercises.html

http://www.englishlearner.com/intermediate/    Open cloze and others

http://www.talkingpeople.net/tp/exercises/reading/index.html     Multiple choice cloze and more

http://www.english-grammar.at/online_exercises/open-cloze/open-cloze-index.htm