In the Chicago area, try the "Common Times." This publication has just about every Chicagoland venue for singarounds, coffee houses, open mics, songwriter collectives (sounds subversive!), and folklore societies. It took me 6 months to find a copy of this gem but it is comprehensive and I commend it to anyone visiting the area.
The contributing folk clubs include The Fox Valley, Lake County, and Downers Grove/Plank Road Folklore Societies. A couple of Mudcatters seem to be mentioned (Jim Bartholemew springs to mind)
Check it out.
Cheers,
Brian