Split out of #461 (closed) (see that issue for motivation):

What might be useful is some kind of strength/reliability/meshing indicator for a forum (either shown in the titlebar, or on a separate about page) calculated from the available metrics (how many contacts you are sharing the forum with, and for each of them how long it has been since you received forum messages synced from them - perhaps the last two sync times). I'm thinking of something along the lines of Stack Exchange's Area 51 proposal commitment score, where the commitment fraction of each user decays over time but is renewed when they visit the proposal again. In our case, we could design it so that when one contact is syncing daily or a few are syncing every few days it shows "good", while for only one contact that last synced a month it would show "poor" (and maybe a third intermediate "okay" level).