I don't know any promoters personally, but here's a list of possible venues I thought of to check out for the Detroit area:
Blondies, Detroit -
http://www.myspace.com/officialblondiesnightclub
I've been to many shows here, ranging from bands like Burst, Powerglove, Moonspell, etc. playing to crowds of a couple dozen people, to shows of a couple hundred people like Kreator/Voivod, Finntroll, Deicide, etc.
Magic Stick/Majestic Theatre, Detroit -
http://majesticdetroit.com/magic-stick/
Never been to the Magic Stick, but it's basically the second floor of the Majestic Theatre, where I've seen bands like Carcass and Between the Buried and Me/Cynic/Devin Townsend Project
The Pike Room/The Crofoot, Pontiac -
http://www.thecrofoot.com/
Also haven't been to the Pike Room, but it's another second level venue at the Crofoot, where I saw Mastodon play on their Crack the Skye tour
I-Rock Nightclub, Detroit -
http://www.irocknightclub.com/
I STILL haven't been here, but it's just a couple blocks down Harper Ave from the infamous Harpos (which I guess you could look into as well!
)
Other possibilities that I'm not gonna comment on individually (partially 'cause I haven't actually been to them yet either!):
The Ritz, Warren -
http://www.myspace.com/theritzdetroit
The Hayloft, Mt Clemens -
http://www.myspace.com/thehayloftvenue
The Token Lounge, Westland -
http://thetokenlounge.com/
(PS - I love how nearly every one of the venues' websites say they are the PREMIERE live venue of Metro Detroit...
)