Strange Horizons launched at Worldcon 2000, fifteen years ago. I briefly considered trying to organize an SH party at this year's Worldcon, but decided I didn't have the energy to do it. But still, I think it's worth acknowledging the anniversary.
(The specific launch date was September 1, so there's still a few days before the calendrical anniversary, but the con anniversary is now.)
SH is the longest-running online prozine, by quite a bit. I'm very pleased that it's still going strong, all these years later.