Exercises here:

http://www.ego4u.com/en/cram-up/grammar/prepersim-preperpro

http://www.englishpage.com/verbpage/verbs8.htm

http://www.englishgrammarsecrets.com/presentperfectsimpleorcontinuous/menu.php

http://www.perfect-english-grammar.com/present-perfect-present-perfect-continuous-1.html

http://esl.about.com/library/quiz/blperfectorperfectcont1.htm

http://www.learn4good.com/languages/evrd_grammar/presentpcont_exc.htm