The Arcade in Brighton Michigan also has a monthly pinball league. We just finished season 1 up last week. There were over 65 participants in season 1 and we will be starting it up again in September or October. If you are interested in the league send me a PM or email at [email protected] and we will put you on the email list.
Here is some more info also:
http://michiganpinball.com/thearcade