Google Groups: Science-Fiction:The science fiction and fantasy bulletin board on search engine Google.
Chronicles Network: Science fiction and fantasy forums, covering literature, films, TV and writing.
Ex Isle: A messageboard for friendly science fiction enthusiasts.
Hard Science Fiction: Discussion forum for fans of hard SF.
Science Fiction Land: Short science fiction genre discussions.
Science Fiction Readers: For fans interested in reading and writing science fiction. Community site with forums, reviews and wikis.
SciFi Forums: Online community with its focus on the media and TV side of SFF.
SciFi.com: BBoard: Chat based about SFF genre TV, movie and book topics.
SF Announcements: Bulletin board for posting news and announcements related to SFF.
SFcrowsnest.com: Communities: Bulletin boards on topics such as author JG Ballard and the TV series Doctor Who.
SFF Net: Online community of genre authors, publishers, editors, and readers. Includes the chat system for the Science Fiction and Fantasy Writers of America.
SFsignal: Science fiction and fantasy blog including news, reviews and points of view.
The Guild of Fantasy Writers: Bulletin board-based chat for fantasy and SF writers, poets and artists. Works can be posted and critiqued by other members.
UK Fantasy Database: SFF books with information on authors, reviews and a forum to ask questions