This is very recent (last few months), and it's the first time ever using trello for any of us, so we don't really have a solid workflow yet, but we have lists for each character, and another for plot-points, etc.

We also have a "GM questions" list for things like "Can I use expansion ruleset X" or "I have an idea for a new Y for your approval" or "How do you house-rule Z"

We are just getting ready to startup a new game, and I've been quite impressed with how it works during startup. In a typical game I've played in the past, characters will get joint backstory when two players are informally talking about their character concepts. With this, players can draft their character concepts in a shared space and I've seen more joint-backstory than typical (though not quite as much as when all players lived on the same floor of a dormitory in college, but that's a level of intimacy most groups don't have).