Will and be going to exercises

http://www.englisch-hilfen.de/en/exercises/tenses/will_going_to_future.htm

http://a4esl.org/q/h/0101/sv-goingto.html

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

http://www.ego4u.com/en/cram-up/grammar/future-1-going-to/exercises