Google Groups: Science-Fiction -  .

Chronicles Network - - Science fiction and fantasy forums, covering literature, films, TV and writing.

Ex Isle - - A messageboard for friendly science fiction enthusiasts.

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.

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.

UK Fantasy Database - - SFF books with information on authors, reviews and a forum to ask question.