Science fiction is a rare bird. I don't know of any genre that has created such a loyal and active fan base. Since Amazing Stories started a letters column back in the early 1920s, sf fans have been corresponding, arguing, publishing fanzines, and organizing meetings and conventions. Fans of other genres do this too, but not with the energy and longevity that sf fans do.
This is why this week's Website for Writers is The Fanac Fan History Project. "Fanac" is fanspeak for "fan activity", and a dictionary of fannish terminology is just one of the many goodies you'll find here. You'll also find various histories of fandom, photos from old gatherings and conventions, and lots of info on Worldcon, the granddaddy of all sf conventions that's been going since 1939.
My favorite section is for fanzines, with many rarities scanned in their entirety. I did a zine of my own back in the Nineties and I've always loved them, so I come back to this section regularly. Some famous names crop up in their pages, but they weren't famous back then!
Dedicated science fiction fans and writers will already know about this website. I'm really suggesting this to writers not in the community, so they can see what's possible. The world of sf fandom is a warm and welcoming place, and other genres need to encourage their own communities. A lot of great writers have risen from the ranks of fandom, and it's always nice to be in a network of folks with the same interests.