I posted a lot on Angel's Soul, but it was mainly a spoiler board, and shipper focused. I remember Tim Minear posting on it in response to Angel fans being upset about Spike joining the show. The show's writers frequented Angel's Soul, and Bronze Beta -- mainly to see the degree to which the series was being spoiled and interact with the fans.
Not so much BC&S though. Although that board had some serious spoiler sources. They actually got on-set pictures of Dark Willow prior to the episode airing. (I didn't consider that I spoiler, since I wanted it to happen and was pretty certain it would - so sought out spoilers to ensure it did. LOL!)