There is a Detroit area meet thread, though no one has really planned or organized a specific meet in quite some time. There are also a few subie guys who hang out on michiganace.com...mostly just in the chatbox all day to keep busy during the boring parts of their day.
Woodward is probably the only regular thing that happens in the summer. Friday and Saturday evenings until the police roll through and tell everyone to go home. I used to be out there pretty often when I was in Royal Oak and Madison Heights. Now that I'm up on Clarkston it's a bit more difficult to get down there on a regular basis. I may make it out a few times this summer, but it'll most likely be in my girlfriend's JCW Cooper S as I don't have a Subaru anymore and the Miata isn't worth "cruising" in.