1. Becoming an Earthling
Probably not of interest to most people, but useful to have as a place to point people who ask about this.
If you want to join the earth.li rabble you need to find 2 existing members who will sponsor you. These should be people who know you reasonably well - you're relying on them to convince others who may not have met you that you'd be a good addition. earth.li is a community and it's much easier to turn someone down and let them in later once we know them better than let them in and realize they don't get on with the rest of us.
After you've got your sponsors you need to email firstname.lastname@example.org letting me know who they are and why you'd like to join us. After that you wait while we have a fight that goes off on a tangent and eventually remember what started off the discussion and move to an electronic vote. Expect a few questions most probably as people try to decide what you're like, and be prepared to wait quite a while for a result to come back. It /really/ helps if you've met a reasonable number of us before, though this is getting harder to manage as we spread out (and take over the world..).
Although very occasionally an earthling might suggest to you that they think you'd make a good earthling and that you might want to consider applying, there is no formal process of "inviting" people so if you are interested then go ahead and try to find sponsors. If you're trying to decide whether earthlings is for you then BeingAnEarthling might help. We do like getting new members, though we are keen to maintain ourselves as a fairly cohesive group so we do consider each possible new earthling fairly carefully. You don't have to have any special qualities or anything, just to be an interesting person who gets on well with or is likely to get on well with most earthlings.
All that sounds very negative. We do like new, interesting, blood. Honest. It gives us an excuse to meet up and go to the pub if nothing else.