Are we assuming a "consistent" alternate universe? One of my "what-if"s from the other thread could certainly be continued, the other was intended as a one-off. Also got one in progress that would be a one-off as well.
So I guess the question is, are you looking more for "continuing stories in an alternate universe, where your characters did something very different and now have a different story to tell", or more at a twilight zone vibe, where you change one thing, get a dramatically different story, but not necessarily one that could continue. Any of the ones where the main character (usually your PC) dies fall into this category.
I would think it's anything that's not the "main universe" but giving enough background so we know which alt universe is happening.