Present simple
http://www.ego4u.com/en/cram-up/tests
http://www.really-learn-english.com/simple-present-exercises.html
http://www.agendaweb.org/verbs/present_simple-exercises.html
http://www.englisch-hilfen.de/en/exercises_list/zeitformen.htm
http://www.myenglishpages.com/site_php_files/grammar-exercise-simple-present.php#.VPqudnyG_pw
http://www.perfect-english-grammar.com/simple-present-exercises.html
http://www.englishpage.com/verbpage/verbtenseintro.html
http://www.english-4u.de/present_ex1.htm
Present continuous
http://www.english-4u.de/present_ex1.htm
http://www.perfect-english-grammar.com/present-continuous-exercise-6.html
http://www.ego4u.com/en/cram-up/tests
http://www.englishpage.com/verbpage/presentcontinuous.html
http://www.englisch-hilfen.de/en/exercises_list/alle_grammar.htm
http://www.really-learn-english.com/present-progressive-exercises.html