Coffee House Coders is a programmer's group that meets Wednesday nights at ERC State St in Ann Arbor. A large long table in the back hosts a dozen or so laptops, and the assembled crowd works on whatever code they are working on.
Organized by Zach Steindler and Matt Pizzimenti, this group when I visited last week was mostly current and recent UM engineering students, with a few people from out of town visiting old friends. I saw a demo of a new product under development by Occiptal, which looked kind of like Doom set in cities, designed to run on a mobile phone.
One notable aspect of Coffee House Coders is that they don't try to create an existence for the group between meetings; there's no ongoing email list as such for discussion, and no permanent home on the web for chit-chat. To make up for that, their network is online and connected when the meeting happens via IRC (irc.freenode.net, channel #coffeehousecoders; I used Mibbit as a client), Twitter (#coffeehousecoders), and Skype (coffeehousecoders).
update: add both zach and matt's names.