It seems that there are more and more Facebook groups popping up. (It's a lot easier than getting a domain and setting up a message board) I'd love to compile a list of these. Some are the larger established clubs, others seem more focused on a single course.
Here are some of what I've found-
Discontinuum https://www.facebook.com/discontinuum
FVM https://www.facebook.com/groups/219384618112164/
DGU https://www.facebook.com/groups/DiscGolfersUnion/
Grabm https://www.facebook.com/groups/300213422580 https://www.facebook.com/pages/GRABM-Greater-Rockford-Area-Bush-Masters/122076393119
Jtown https://www.facebook.com/pages/J-Town-Disc-Golf-Club/144615498936161
Marengo Disc Golf https://www.facebook.com/groups/marengoDG/
Freeport Frisbee Fanatics https://www.facebook.com/groups/144452502246839/
DeKalb https://www.facebook.com/groups/199327750165163/
Sinnissippi Disc Golf https://www.facebook.com/groups/219588584809419/
Disc Golf Pond Crawlers https://www.facebook.com/groups/86570766143/
Valet Kings https://www.facebook.com/valetkings