This is a little exercise I've been wanting to start here: Think of movies you love, or movies you've seen recently and see if you can identify the act breaks! Maybe this isn't your idea of fun, but it is mine! (though I actually suck at it). For even more fun, see if you can identify how trilogies can form macro Acts.
I started the question for the OT over here: http://originaltrilogy.com/forum/topic.cfm/Original-Trilogy-Times-Chart/post/412779/#TopicPost412779