Right now, campaigns log the chat, which is really cool. But it's incomplete. I would like to suggest a few additional things. For one, showing when things are added to player journals, and letting people read them if they're available to everyone.
The bigger and more unlikely thing is, since many games are done with voice and not the chat, audio recordings of the games. Obviously, the issue of server space comes up here, so perhaps to deal with this, the audio logs could be uploaded to the spot of the GM's choice instead of saved forever, and the GM could choose to make those available. I understand that this is complicated, but I just wanted to put it out there that I would love to have it available, if it is possible.