To me, some of the benefits of having the occasional meeting is to create a shared understanding of what's going on and also to enable a vigorous group discussion. I'm not sure I would know how to replicate that with writing alone.
Chatrooms for each team, but visible to other teams. And a culture of encouraging technical discussion to be summarized or at least alluded to in the public chat. I'm sure this doesn't scale, but for a company of <20 developers, this worked amazingly.
It was also great for finding answers to silly questions without having to bug someone.
