With respect to Robert Cartaino's answer on the hilariously-titled question, This site is doomed and will curl up and die — the sunshine-and-hope thread, SciFi.SE needs to come up with an elevator pitch.
An elevator pitch is a short, 1-2 minute (although Robert suggests 5-10 seconds) schtick you can memorize and deliver to someone in an elevator when they ask, "What is the Science Fiction Stack Exchange site about?"
It's meant to distill down the core essence of the product so a person, before they get to their floor, fully understands what it is you're trying to do and, ideally, is convinced what you're trying to do is awesome and immensely worthwhile.
So what would be our elevator pitch? What is quintessentially SciFi.SE material, and what is categorically not? Why would a layperson who wasn't involved in the proposal ever want to visit and keep coming back?