A quest journal
Every MMO has a "quest journal". But it is not really a "journal". It is an interface element - a button you press to see all of your current quests. What if instead of that, we had... An actual journal? A book that you carry with you, where your character makes notes about things that happened to him during the day. To get notes like this your character would have to fill the journal. So you go through some adventures, and then you go to, say, a tavern, sit down, click "add records to the journal" and these notes appear. They appear on their own, you don't write them - your character "writes" them. But they reflect real events that happened to you and serve as a less convenient but more realistic and immersive replacement for a quest journal.
Instead of "We are overrun with boars. Go kill 10 boars. Boars killed 0/10" it would say something like:
"The villagers are surely hiding something. I might want to go and take a look at that "circle" they mentioned - some answers could be hidden there. Also, that boy in the corner kept giving me looks..."
In conventional quest "journals" there is also a list of quests you are currently on, and you can always get the "notes" (in reality just the dialog) correlating to the quest you click on. I don't know if it would be good to break that structure, and make all the notes straight up chronological. It would make the journal less convenient, but on the other hand will make you pay way more attention when you are reading the quests, as well as when you are reading the journal itself. You surely will need some list - or you'll be completely confused, but it can be a list of quest names with short descriptions, and to refresh the details you'll have to read the actual notes your character has made.
The Great Black Wolf
A beast hunting caravans
You can't click on it, nothing would happen. But somewhere in your journal there is a note.
05/03
Talked to the blacksmith this afternoon. He says last time the beast was seen crossing the road near Buklava village. If he is hunting the next caravan, as the mayor fears, the suspicion rightly falls on the deepest parts of the Creshin Woods - his lair must be in there somewhere. I should go talk to local Buklava foresters.
The journal can possibly include other players, and also some things that have nothing to do with any quests at all. Let's say you killed a dragon-boss.
07/09
This night people are celebrating all other the Planes of Bristol, as the dragon haunting their cattle is defeated at last. It took 53 men, 14 of whom are only still seeing the light of day by the good graces of Goddess of Creation herself, and otherwise would be dead. Volhovets of Aurora Borelias has lead us to this great victory, and many honorable warriors of "The Legacy" has thought today besides us.
What do you think?