Name
membership
/guest/view
link
discussion forums seen/visited by cresby.com
Mudcat Cafe
guest/member
Folk & BS Forum
My favourite, search/add/request for lyrics/background, or just general chat (BS). Worldwide with a healthy UK membership. If you have a folklore question search first, then post a question, but tell 'em what you already know (or think)- it saves time. You will get answers.
the Annex
member/view
forum
Uses the same login/identity as the Mudcat but does not allow guests (thank goodness)
Folk Info
member/view
forum
UK based - have a look.
Tradsong
member/view
forum
more for serious discussion on Folk related items, or talk about people in the genre (past & present), + events and gatherings on the more erudite aspects thereto.
Folk Radio
member/view
forum
formerly the webradio station Radio Britfolk, their discussion is general & sometimes based on their content.
Somerset & Dorset
member/view
forum
General talk/announcments for Somerset & Dorset
Costwolds
member/view
forum mostly reminders of calendar based info of Cotswolds. But if you can ask questions.
Didmarton
member/view
forum
Mostly about the Didmarton Bluegrass Festival but includes news of Bluegrass in the wider area nearby.
Covfolk 
 
forum Discussions about Coventry & environs' folk.
Allceilidh
member/view
forum
ceilidh based discussion, though it is fairly relaxed about discussions. Look at the posts.
Eceilidh
member
e-mail them
e-mail based discussion. The listmeister rules with an iron hand, note: Scottish, contra (zesty or not), Cajun, French/Breton, or Morris is not tolerated as a topic for discussion. Only English ceilidh issues.
BBC
member/view
you'll find it Folk and acoustic. It has devolved to a territory of commercial stuff. Concerts, records and the single BBC R2 prog. If you try it and don't enjoy it, don't say you weren't warned. Folklore it ain't. Go Directly to the Mudcat and compare!